rewriteHandler.c File Reference

#include "postgres.h"
#include "access/relation.h"
#include "access/sysattr.h"
#include "access/table.h"
#include "catalog/dependency.h"
#include "commands/trigger.h"
#include "executor/executor.h"
#include "foreign/fdwapi.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/optimizer.h"
#include "parser/analyze.h"
#include "parser/parse_coerce.h"
#include "parser/parse_relation.h"
#include "parser/parsetree.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rewriteGraphTable.h"
#include "rewrite/rewriteHandler.h"
#include "rewrite/rewriteManip.h"
#include "rewrite/rewriteSearchCycle.h"
#include "rewrite/rowsecurity.h"
#include "tcop/tcopprot.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"

Include dependency graph for rewriteHandler.c:

Go to the source code of this file.

Data Structures
struct	rewrite_event
struct	acquireLocksOnSubLinks_context
struct	fireRIRonSubLink_context

Macros
#define	ALL_EVENTS   ((1 << CMD_INSERT) | (1 << CMD_UPDATE) | (1 << CMD_DELETE))

Typedefs
typedef struct rewrite_event	rewrite_event
typedef struct acquireLocksOnSubLinks_context	acquireLocksOnSubLinks_context
typedef struct fireRIRonSubLink_context	fireRIRonSubLink_context

Functions
static bool	acquireLocksOnSubLinks (Node *node, acquireLocksOnSubLinks_context *context)
static Query *	rewriteRuleAction (Query *parsetree, Query *rule_action, Node *rule_qual, int rt_index, CmdType event, bool *returning_flag)
static List *	adjustJoinTreeList (Query *parsetree, bool removert, int rt_index)
static List *	rewriteTargetListIU (List *targetList, CmdType commandType, OverridingKind override, Relation target_relation, RangeTblEntry *values_rte, int values_rte_index, Bitmapset **unused_values_attrnos)
static TargetEntry *	process_matched_tle (TargetEntry *src_tle, TargetEntry *prior_tle, const char *attrName)
static Node *	get_assignment_input (Node *node)
static Bitmapset *	findDefaultOnlyColumns (RangeTblEntry *rte)
static bool	rewriteValuesRTE (Query *parsetree, RangeTblEntry *rte, int rti, Relation target_relation, Bitmapset *unused_cols)
static void	rewriteValuesRTEToNulls (Query *parsetree, RangeTblEntry *rte)
static void	markQueryForLocking (Query *qry, Node *jtnode, LockClauseStrength strength, LockWaitPolicy waitPolicy, bool pushedDown)
static List *	matchLocks (CmdType event, Relation relation, int varno, Query *parsetree, bool *hasUpdate)
static Query *	fireRIRrules (Query *parsetree, List *activeRIRs)
static Bitmapset *	adjust_view_column_set (Bitmapset *cols, List *targetlist)
static Node *	expand_generated_columns_internal (Node *node, Relation rel, int rt_index, RangeTblEntry *rte, int result_relation)
void	AcquireRewriteLocks (Query *parsetree, bool forExecute, bool forUpdatePushedDown)
Node *	build_column_default (Relation rel, int attrno)
static bool	searchForDefault (RangeTblEntry *rte)
static Query *	ApplyRetrieveRule (Query *parsetree, RewriteRule *rule, int rt_index, Relation relation, List *activeRIRs)
static bool	fireRIRonSubLink (Node *node, fireRIRonSubLink_context *context)
static Query *	CopyAndAddInvertedQual (Query *parsetree, Node *rule_qual, int rt_index, CmdType event)
static List *	fireRules (Query *parsetree, int rt_index, CmdType event, List *locks, bool *instead_flag, bool *returning_flag, Query **qual_product)
Query *	get_view_query (Relation view)
bool	view_has_instead_trigger (Relation view, CmdType event, List *mergeActionList)
static const char *	view_col_is_auto_updatable (RangeTblRef *rtr, TargetEntry *tle)
const char *	view_query_is_auto_updatable (Query *viewquery, bool check_cols)
static const char *	view_cols_are_auto_updatable (Query *viewquery, Bitmapset *required_cols, Bitmapset **updatable_cols, char **non_updatable_col)
int	relation_is_updatable (Oid reloid, List *outer_reloids, bool include_triggers, Bitmapset *include_cols)
void	error_view_not_updatable (Relation view, CmdType command, List *mergeActionList, const char *detail)
static Query *	rewriteTargetView (Query *parsetree, Relation view)
static List *	RewriteQuery (Query *parsetree, List *rewrite_events, int orig_rt_length, int num_ctes_processed)
Node *	expand_generated_columns_in_expr (Node *node, Relation rel, int rt_index)
Node *	build_generation_expression (Relation rel, int attrno)
List *	QueryRewrite (Query *parsetree)

Macro Definition Documentation

ALL_EVENTS

#define ALL_EVENTS   ((1 << CMD_INSERT) | (1 << CMD_UPDATE) | (1 << CMD_DELETE))

Typedef Documentation

acquireLocksOnSubLinks_context

typedef struct acquireLocksOnSubLinks_context acquireLocksOnSubLinks_context

fireRIRonSubLink_context

typedef struct fireRIRonSubLink_context fireRIRonSubLink_context

rewrite_event

typedef struct rewrite_event rewrite_event

Function Documentation

acquireLocksOnSubLinks()

static bool acquireLocksOnSubLinks ( Node *  node, acquireLocksOnSubLinks_context *  context  )

static

Definition at line 312 of file rewriteHandler.c.

{
    if (node == NULL)
        return false;
    if (IsA(node, SubLink))
    {
        SubLink    *sub = (SubLink *) node;
 
        /* Do what we came for */
        AcquireRewriteLocks((Query *) sub->subselect,
                            context->for_execute,
                            false);
        /* Fall through to process lefthand args of SubLink */
    }
 
    /*
     * Do NOT recurse into Query nodes, because AcquireRewriteLocks already
     * processed subselects of subselects for us.
     */
    return expression_tree_walker(node, acquireLocksOnSubLinks, context);
}

References acquireLocksOnSubLinks(), AcquireRewriteLocks(), expression_tree_walker, fb(), acquireLocksOnSubLinks_context::for_execute, IsA, and SubLink::subselect.

Referenced by acquireLocksOnSubLinks(), AcquireRewriteLocks(), CopyAndAddInvertedQual(), fireRIRrules(), rewriteRuleAction(), and rewriteTargetView().

AcquireRewriteLocks()

void AcquireRewriteLocks	(	Query *	parsetree,
		bool	forExecute,
		bool	forUpdatePushedDown
	)

Definition at line 149 of file rewriteHandler.c.

{
    ListCell   *l;
    int         rt_index;
    acquireLocksOnSubLinks_context context;
 
    context.for_execute = forExecute;
 
    /*
     * First, process RTEs of the current query level.
     */
    rt_index = 0;
    foreach(l, parsetree->rtable)
    {
        RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
        Relation    rel;
        LOCKMODE    lockmode;
        List       *newaliasvars;
        Index       curinputvarno;
        RangeTblEntry *curinputrte;
        ListCell   *ll;
 
        ++rt_index;
        switch (rte->rtekind)
        {
            case RTE_RELATION:
            case RTE_GRAPH_TABLE:
 
                /*
                 * Grab the appropriate lock type for the relation, and do not
                 * release it until end of transaction.  This protects the
                 * rewriter, planner, and executor against schema changes
                 * mid-query.
                 *
                 * If forExecute is false, ignore rellockmode and just use
                 * AccessShareLock.
                 */
                if (!forExecute)
                    lockmode = AccessShareLock;
                else if (forUpdatePushedDown)
                {
                    /* Upgrade RTE's lock mode to reflect pushed-down lock */
                    if (rte->rellockmode == AccessShareLock)
                        rte->rellockmode = RowShareLock;
                    lockmode = rte->rellockmode;
                }
                else
                    lockmode = rte->rellockmode;
 
                rel = relation_open(rte->relid, lockmode);
 
                /*
                 * While we have the relation open, update the RTE's relkind,
                 * just in case it changed since this rule was made.
                 */
                rte->relkind = rel->rd_rel->relkind;
 
                relation_close(rel, NoLock);
                break;
 
            case RTE_JOIN:
 
                /*
                 * Scan the join's alias var list to see if any columns have
                 * been dropped, and if so replace those Vars with null
                 * pointers.
                 *
                 * Since a join has only two inputs, we can expect to see
                 * multiple references to the same input RTE; optimize away
                 * multiple fetches.
                 */
                newaliasvars = NIL;
                curinputvarno = 0;
                curinputrte = NULL;
                foreach(ll, rte->joinaliasvars)
                {
                    Var        *aliasitem = (Var *) lfirst(ll);
                    Var        *aliasvar = aliasitem;
 
                    /* Look through any implicit coercion */
                    aliasvar = (Var *) strip_implicit_coercions((Node *) aliasvar);
 
                    /*
                     * If the list item isn't a simple Var, then it must
                     * represent a merged column, ie a USING column, and so it
                     * couldn't possibly be dropped, since it's referenced in
                     * the join clause.  (Conceivably it could also be a null
                     * pointer already?  But that's OK too.)
                     */
                    if (aliasvar && IsA(aliasvar, Var))
                    {
                        /*
                         * The elements of an alias list have to refer to
                         * earlier RTEs of the same rtable, because that's the
                         * order the planner builds things in.  So we already
                         * processed the referenced RTE, and so it's safe to
                         * use get_rte_attribute_is_dropped on it. (This might
                         * not hold after rewriting or planning, but it's OK
                         * to assume here.)
                         */
                        Assert(aliasvar->varlevelsup == 0);
                        if (aliasvar->varno != curinputvarno)
                        {
                            curinputvarno = aliasvar->varno;
                            if (curinputvarno >= rt_index)
                                elog(ERROR, "unexpected varno %d in JOIN RTE %d",
                                     curinputvarno, rt_index);
                            curinputrte = rt_fetch(curinputvarno,
                                                   parsetree->rtable);
                        }
                        if (get_rte_attribute_is_dropped(curinputrte,
                                                         aliasvar->varattno))
                        {
                            /* Replace the join alias item with a NULL */
                            aliasitem = NULL;
                        }
                    }
                    newaliasvars = lappend(newaliasvars, aliasitem);
                }
                rte->joinaliasvars = newaliasvars;
                break;
 
            case RTE_SUBQUERY:
 
                /*
                 * The subquery RTE itself is all right, but we have to
                 * recurse to process the represented subquery.
                 */
                AcquireRewriteLocks(rte->subquery,
                                    forExecute,
                                    (forUpdatePushedDown ||
                                     get_parse_rowmark(parsetree, rt_index) != NULL));
                break;
 
            default:
                /* ignore other types of RTEs */
                break;
        }
    }
 
    /* Recurse into subqueries in WITH */
    foreach(l, parsetree->cteList)
    {
        CommonTableExpr *cte = (CommonTableExpr *) lfirst(l);
 
        AcquireRewriteLocks((Query *) cte->ctequery, forExecute, false);
    }
 
    /*
     * Recurse into sublink subqueries, too.  But we already did the ones in
     * the rtable and cteList.
     */
    if (parsetree->hasSubLinks)
        query_tree_walker(parsetree, acquireLocksOnSubLinks, &context,
                          QTW_IGNORE_RC_SUBQUERIES);
}

References AccessShareLock, acquireLocksOnSubLinks(), AcquireRewriteLocks(), Assert, Query::cteList, CommonTableExpr::ctequery, elog, ERROR, fb(), acquireLocksOnSubLinks_context::for_execute, get_parse_rowmark(), get_rte_attribute_is_dropped(), IsA, lappend(), lfirst, NIL, NoLock, QTW_IGNORE_RC_SUBQUERIES, query_tree_walker, RelationData::rd_rel, relation_close(), relation_open(), RowShareLock, rt_fetch, Query::rtable, RTE_GRAPH_TABLE, RTE_JOIN, RTE_RELATION, RTE_SUBQUERY, and strip_implicit_coercions().

Referenced by acquireLocksOnSubLinks(), AcquireRewriteLocks(), ApplyRetrieveRule(), fmgr_sql_validator(), get_query_def(), inline_sql_function_in_from(), make_ruledef(), prepare_next_query(), print_function_sqlbody(), refresh_matview_datafill(), RevalidateCachedQuery(), rewriteGraphTable(), and rewriteRuleAction().

adjust_view_column_set()

static Bitmapset * adjust_view_column_set ( Bitmapset *  cols, List *  targetlist  )

static

Definition at line 3073 of file rewriteHandler.c.

{
    Bitmapset  *result = NULL;
    int         col;
 
    col = -1;
    while ((col = bms_next_member(cols, col)) >= 0)
    {
        /* bit numbers are offset by FirstLowInvalidHeapAttributeNumber */
        AttrNumber  attno = col + FirstLowInvalidHeapAttributeNumber;
 
        if (attno == InvalidAttrNumber)
        {
            /*
             * There's a whole-row reference to the view.  For permissions
             * purposes, treat it as a reference to each column available from
             * the view.  (We should *not* convert this to a whole-row
             * reference to the base relation, since the view may not touch
             * all columns of the base relation.)
             */
            ListCell   *lc;
 
            foreach(lc, targetlist)
            {
                TargetEntry *tle = lfirst_node(TargetEntry, lc);
                Var        *var;
 
                if (tle->resjunk)
                    continue;
                var = castNode(Var, tle->expr);
                result = bms_add_member(result,
                                        var->varattno - FirstLowInvalidHeapAttributeNumber);
            }
        }
        else
        {
            /*
             * Views do not have system columns, so we do not expect to see
             * any other system attnos here.  If we do find one, the error
             * case will apply.
             */
            TargetEntry *tle = get_tle_by_resno(targetlist, attno);
 
            if (tle != NULL && !tle->resjunk && IsA(tle->expr, Var))
            {
                Var        *var = (Var *) tle->expr;
 
                result = bms_add_member(result,
                                        var->varattno - FirstLowInvalidHeapAttributeNumber);
            }
            else
                elog(ERROR, "attribute number %d not found in view targetlist",
                     attno);
        }
    }
 
    return result;
}

References bms_add_member(), bms_next_member(), castNode, elog, ERROR, fb(), FirstLowInvalidHeapAttributeNumber, get_tle_by_resno(), InvalidAttrNumber, IsA, lfirst_node, result, and Var::varattno.

Referenced by relation_is_updatable(), and rewriteTargetView().

adjustJoinTreeList()

static List * adjustJoinTreeList ( Query *  parsetree, bool  removert, int  rt_index  )

static

Definition at line 728 of file rewriteHandler.c.

{
    List       *newjointree = copyObject(parsetree->jointree->fromlist);
    ListCell   *l;
 
    if (removert)
    {
        foreach(l, newjointree)
        {
            RangeTblRef *rtr = lfirst(l);
 
            if (IsA(rtr, RangeTblRef) &&
                rtr->rtindex == rt_index)
            {
                newjointree = foreach_delete_current(newjointree, l);
                break;
            }
        }
    }
    return newjointree;
}

References copyObject, fb(), foreach_delete_current, FromExpr::fromlist, IsA, Query::jointree, and lfirst.

Referenced by rewriteRuleAction().

ApplyRetrieveRule()

static Query * ApplyRetrieveRule ( Query *  parsetree, RewriteRule *  rule, int  rt_index, Relation  relation, List *  activeRIRs  )

static

Definition at line 1729 of file rewriteHandler.c.

{
    Query      *rule_action;
    RangeTblEntry *rte;
    RowMarkClause *rc;
    int         numCols;
 
    if (list_length(rule->actions) != 1)
        elog(ERROR, "expected just one rule action");
    if (rule->qual != NULL)
        elog(ERROR, "cannot handle qualified ON SELECT rule");
 
    /* Check if the expansion of non-system views are restricted */
    if (unlikely((restrict_nonsystem_relation_kind & RESTRICT_RELKIND_VIEW) != 0 &&
                 RelationGetRelid(relation) >= FirstNormalObjectId))
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("access to non-system view \"%s\" is restricted",
                        RelationGetRelationName(relation))));
 
    if (rt_index == parsetree->resultRelation)
    {
        /*
         * We have a view as the result relation of the query, and it wasn't
         * rewritten by any rule.  This case is supported if there is an
         * INSTEAD OF trigger that will trap attempts to insert/update/delete
         * view rows.  The executor will check that; for the moment just plow
         * ahead.  We have two cases:
         *
         * For INSERT, we needn't do anything.  The unmodified RTE will serve
         * fine as the result relation.
         *
         * For UPDATE/DELETE/MERGE, we need to expand the view so as to have
         * source data for the operation.  But we also need an unmodified RTE
         * to serve as the target.  So, copy the RTE and add the copy to the
         * rangetable.  Note that the copy does not get added to the jointree.
         * Also note that there's a hack in fireRIRrules to avoid calling this
         * function again when it arrives at the copied RTE.
         */
        if (parsetree->commandType == CMD_INSERT)
            return parsetree;
        else if (parsetree->commandType == CMD_UPDATE ||
                 parsetree->commandType == CMD_DELETE ||
                 parsetree->commandType == CMD_MERGE)
        {
            RangeTblEntry *newrte;
            Var        *var;
            TargetEntry *tle;
 
            rte = rt_fetch(rt_index, parsetree->rtable);
            newrte = copyObject(rte);
            parsetree->rtable = lappend(parsetree->rtable, newrte);
            parsetree->resultRelation = list_length(parsetree->rtable);
            /* parsetree->mergeTargetRelation unchanged (use expanded view) */
 
            /*
             * For the most part, Vars referencing the view should remain as
             * they are, meaning that they implicitly represent OLD values.
             * But in the RETURNING list if any, we want such Vars to
             * represent NEW values, so change them to reference the new RTE.
             *
             * Since ChangeVarNodes scribbles on the tree in-place, copy the
             * RETURNING list first for safety.
             */
            parsetree->returningList = copyObject(parsetree->returningList);
            ChangeVarNodes((Node *) parsetree->returningList, rt_index,
                           parsetree->resultRelation, 0);
 
            /*
             * To allow the executor to compute the original view row to pass
             * to the INSTEAD OF trigger, we add a resjunk whole-row Var
             * referencing the original RTE.  This will later get expanded
             * into a RowExpr computing all the OLD values of the view row.
             */
            var = makeWholeRowVar(rte, rt_index, 0, false);
            tle = makeTargetEntry((Expr *) var,
                                  list_length(parsetree->targetList) + 1,
                                  pstrdup("wholerow"),
                                  true);
 
            parsetree->targetList = lappend(parsetree->targetList, tle);
 
            /* Now, continue with expanding the original view RTE */
        }
        else
            elog(ERROR, "unrecognized commandType: %d",
                 (int) parsetree->commandType);
    }
 
    /*
     * Check if there's a FOR [KEY] UPDATE/SHARE clause applying to this view.
     *
     * Note: we needn't explicitly consider any such clauses appearing in
     * ancestor query levels; their effects have already been pushed down to
     * here by markQueryForLocking, and will be reflected in "rc".
     */
    rc = get_parse_rowmark(parsetree, rt_index);
 
    /*
     * Make a modifiable copy of the view query, and acquire needed locks on
     * the relations it mentions.  Force at least RowShareLock for all such
     * rels if there's a FOR [KEY] UPDATE/SHARE clause affecting this view.
     */
    rule_action = copyObject(linitial(rule->actions));
 
    AcquireRewriteLocks(rule_action, true, (rc != NULL));
 
    /*
     * If FOR [KEY] UPDATE/SHARE of view, mark all the contained tables as
     * implicit FOR [KEY] UPDATE/SHARE, the same as the parser would have done
     * if the view's subquery had been written out explicitly.
     */
    if (rc != NULL)
        markQueryForLocking(rule_action, (Node *) rule_action->jointree,
                            rc->strength, rc->waitPolicy, true);
 
    /*
     * Recursively expand any view references inside the view.
     */
    rule_action = fireRIRrules(rule_action, activeRIRs);
 
    /*
     * Make sure the query is marked as having row security if the view query
     * does.
     */
    parsetree->hasRowSecurity |= rule_action->hasRowSecurity;
 
    /*
     * Now, plug the view query in as a subselect, converting the relation's
     * original RTE to a subquery RTE.
     */
    rte = rt_fetch(rt_index, parsetree->rtable);
 
    rte->rtekind = RTE_SUBQUERY;
    rte->subquery = rule_action;
    rte->security_barrier = RelationIsSecurityView(relation);
 
    /*
     * Clear fields that should not be set in a subquery RTE.  Note that we
     * leave the relid, relkind, rellockmode, and perminfoindex fields set, so
     * that the view relation can be appropriately locked before execution and
     * its permissions checked.
     */
    rte->tablesample = NULL;
    rte->inh = false;           /* must not be set for a subquery */
 
    /*
     * Since we allow CREATE OR REPLACE VIEW to add columns to a view, the
     * rule_action might emit more columns than we expected when the current
     * query was parsed.  Various places expect rte->eref->colnames to be
     * consistent with the non-junk output columns of the subquery, so patch
     * things up if necessary by adding some dummy column names.
     */
    numCols = ExecCleanTargetListLength(rule_action->targetList);
    while (list_length(rte->eref->colnames) < numCols)
    {
        rte->eref->colnames = lappend(rte->eref->colnames,
                                      makeString(pstrdup("?column?")));
    }
 
    return parsetree;
}

References AcquireRewriteLocks(), ChangeVarNodes(), CMD_DELETE, CMD_INSERT, CMD_MERGE, CMD_UPDATE, Query::commandType, copyObject, elog, ereport, errcode(), errmsg, ERROR, ExecCleanTargetListLength(), fb(), fireRIRrules(), FirstNormalObjectId, get_parse_rowmark(), lappend(), linitial, list_length(), makeString(), makeTargetEntry(), makeWholeRowVar(), markQueryForLocking(), pstrdup(), RelationGetRelationName, RelationGetRelid, RelationIsSecurityView, restrict_nonsystem_relation_kind, RESTRICT_RELKIND_VIEW, Query::returningList, rt_fetch, Query::rtable, RTE_SUBQUERY, RowMarkClause::strength, Query::targetList, unlikely, and RowMarkClause::waitPolicy.

Referenced by fireRIRrules().

build_column_default()

Node * build_column_default	(	Relation	rel,
		int	attrno
	)

Definition at line 1246 of file rewriteHandler.c.

{
    TupleDesc   rd_att = rel->rd_att;
    Form_pg_attribute att_tup = TupleDescAttr(rd_att, attrno - 1);
    Oid         atttype = att_tup->atttypid;
    int32       atttypmod = att_tup->atttypmod;
    Node       *expr = NULL;
    Oid         exprtype;
 
    if (att_tup->attidentity)
    {
        NextValueExpr *nve = makeNode(NextValueExpr);
 
        nve->seqid = getIdentitySequence(rel, attrno, false);
        nve->typeId = att_tup->atttypid;
 
        return (Node *) nve;
    }
 
    /*
     * If relation has a default for this column, fetch that expression.
     */
    if (att_tup->atthasdef)
    {
        expr = TupleDescGetDefault(rd_att, attrno);
        if (expr == NULL)
            elog(ERROR, "default expression not found for attribute %d of relation \"%s\"",
                 attrno, RelationGetRelationName(rel));
    }
 
    /*
     * No per-column default, so look for a default for the type itself.  But
     * not for generated columns.
     */
    if (expr == NULL && !att_tup->attgenerated)
        expr = get_typdefault(atttype);
 
    if (expr == NULL)
        return NULL;            /* No default anywhere */
 
    /*
     * Make sure the value is coerced to the target column type; this will
     * generally be true already, but there seem to be some corner cases
     * involving domain defaults where it might not be true. This should match
     * the parser's processing of non-defaulted expressions --- see
     * transformAssignedExpr().
     */
    exprtype = exprType(expr);
 
    expr = coerce_to_target_type(NULL,  /* no UNKNOWN params here */
                                 expr, exprtype,
                                 atttype, atttypmod,
                                 COERCION_ASSIGNMENT,
                                 COERCE_IMPLICIT_CAST,
                                 -1);
    if (expr == NULL)
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("column \"%s\" is of type %s"
                        " but default expression is of type %s",
                        NameStr(att_tup->attname),
                        format_type_be(atttype),
                        format_type_be(exprtype)),
                 errhint("You will need to rewrite or cast the expression.")));
 
    return expr;
}

References COERCE_IMPLICIT_CAST, coerce_to_target_type(), COERCION_ASSIGNMENT, elog, ereport, errcode(), errhint(), errmsg, ERROR, exprType(), fb(), format_type_be(), get_typdefault(), getIdentitySequence(), makeNode, NameStr, RelationData::rd_att, RelationGetRelationName, TupleDescAttr(), and TupleDescGetDefault().

Referenced by ATExecAddColumn(), ATExecAlterColumnType(), ATExecSetExpression(), BeginCopyFrom(), build_generation_expression(), ExecInitGenerated(), rewriteTargetListIU(), rewriteValuesRTE(), and slot_fill_defaults().

build_generation_expression()

Node * build_generation_expression	(	Relation	rel,
		int	attrno
	)

Definition at line 4619 of file rewriteHandler.c.

{
    TupleDesc   rd_att = RelationGetDescr(rel);
    Form_pg_attribute att_tup = TupleDescAttr(rd_att, attrno - 1);
    Node       *defexpr;
    Oid         attcollid;
 
    Assert(rd_att->constr && rd_att->constr->has_generated_virtual);
    Assert(att_tup->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL);
 
    defexpr = build_column_default(rel, attrno);
    if (defexpr == NULL)
        elog(ERROR, "no generation expression found for column number %d of table \"%s\"",
             attrno, RelationGetRelationName(rel));
 
    /*
     * If the column definition has a collation and it is different from the
     * collation of the generation expression, put a COLLATE clause around the
     * expression.
     */
    attcollid = att_tup->attcollation;
    if (attcollid && attcollid != exprCollation(defexpr))
    {
        CollateExpr *ce = makeNode(CollateExpr);
 
        ce->arg = (Expr *) defexpr;
        ce->collOid = attcollid;
        ce->location = -1;
 
        defexpr = (Node *) ce;
    }
 
    return defexpr;
}

References Assert, build_column_default(), TupleDescData::constr, elog, ERROR, exprCollation(), fb(), TupleConstr::has_generated_virtual, makeNode, RelationGetDescr, RelationGetRelationName, and TupleDescAttr().

Referenced by createTableConstraints(), ExecRelGenVirtualNotNull(), expand_generated_columns_internal(), and expand_virtual_generated_columns().

CopyAndAddInvertedQual()

static Query * CopyAndAddInvertedQual ( Query *  parsetree, Node *  rule_qual, int  rt_index, CmdType  event  )

static

Definition at line 2348 of file rewriteHandler.c.

{
    /* Don't scribble on the passed qual (it's in the relcache!) */
    Node       *new_qual = copyObject(rule_qual);
    acquireLocksOnSubLinks_context context;
 
    context.for_execute = true;
 
    /*
     * In case there are subqueries in the qual, acquire necessary locks and
     * fix any deleted JOIN RTE entries.  (This is somewhat redundant with
     * rewriteRuleAction, but not entirely ... consider restructuring so that
     * we only need to process the qual this way once.)
     */
    (void) acquireLocksOnSubLinks(new_qual, &context);
 
    /* Fix references to OLD */
    ChangeVarNodes(new_qual, PRS2_OLD_VARNO, rt_index, 0);
    /* Fix references to NEW */
    if (event == CMD_INSERT || event == CMD_UPDATE)
        new_qual = ReplaceVarsFromTargetList(new_qual,
                                             PRS2_NEW_VARNO,
                                             0,
                                             rt_fetch(rt_index,
                                                      parsetree->rtable),
                                             parsetree->targetList,
                                             parsetree->resultRelation,
                                             (event == CMD_UPDATE) ?
                                             REPLACEVARS_CHANGE_VARNO :
                                             REPLACEVARS_SUBSTITUTE_NULL,
                                             rt_index,
                                             &parsetree->hasSubLinks);
    /* And attach the fixed qual */
    AddInvertedQual(parsetree, new_qual);
 
    return parsetree;
}

References acquireLocksOnSubLinks(), AddInvertedQual(), ChangeVarNodes(), CMD_INSERT, CMD_UPDATE, copyObject, fb(), acquireLocksOnSubLinks_context::for_execute, PRS2_NEW_VARNO, PRS2_OLD_VARNO, REPLACEVARS_CHANGE_VARNO, REPLACEVARS_SUBSTITUTE_NULL, ReplaceVarsFromTargetList(), rt_fetch, Query::rtable, and Query::targetList.

Referenced by fireRules().

error_view_not_updatable()

void error_view_not_updatable	(	Relation	view,
		CmdType	command,
		List *	mergeActionList,
		const char *	detail
	)

Definition at line 3147 of file rewriteHandler.c.

{
    TriggerDesc *trigDesc = view->trigdesc;
 
    switch (command)
    {
        case CMD_INSERT:
            ereport(ERROR,
                    errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                    errmsg("cannot insert into view \"%s\"",
                           RelationGetRelationName(view)),
                    detail ? errdetail_internal("%s", _(detail)) : 0,
                    errhint("To enable inserting into the view, provide an INSTEAD OF INSERT trigger or an unconditional ON INSERT DO INSTEAD rule."));
            break;
        case CMD_UPDATE:
            ereport(ERROR,
                    errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                    errmsg("cannot update view \"%s\"",
                           RelationGetRelationName(view)),
                    detail ? errdetail_internal("%s", _(detail)) : 0,
                    errhint("To enable updating the view, provide an INSTEAD OF UPDATE trigger or an unconditional ON UPDATE DO INSTEAD rule."));
            break;
        case CMD_DELETE:
            ereport(ERROR,
                    errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                    errmsg("cannot delete from view \"%s\"",
                           RelationGetRelationName(view)),
                    detail ? errdetail_internal("%s", _(detail)) : 0,
                    errhint("To enable deleting from the view, provide an INSTEAD OF DELETE trigger or an unconditional ON DELETE DO INSTEAD rule."));
            break;
        case CMD_MERGE:
 
            /*
             * Note that the error hints here differ from above, since MERGE
             * doesn't support rules.
             */
            foreach_node(MergeAction, action, mergeActionList)
            {
                switch (action->commandType)
                {
                    case CMD_INSERT:
                        if (!trigDesc || !trigDesc->trig_insert_instead_row)
                            ereport(ERROR,
                                    errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                    errmsg("cannot insert into view \"%s\"",
                                           RelationGetRelationName(view)),
                                    detail ? errdetail_internal("%s", _(detail)) : 0,
                                    errhint("To enable inserting into the view using MERGE, provide an INSTEAD OF INSERT trigger."));
                        break;
                    case CMD_UPDATE:
                        if (!trigDesc || !trigDesc->trig_update_instead_row)
                            ereport(ERROR,
                                    errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                    errmsg("cannot update view \"%s\"",
                                           RelationGetRelationName(view)),
                                    detail ? errdetail_internal("%s", _(detail)) : 0,
                                    errhint("To enable updating the view using MERGE, provide an INSTEAD OF UPDATE trigger."));
                        break;
                    case CMD_DELETE:
                        if (!trigDesc || !trigDesc->trig_delete_instead_row)
                            ereport(ERROR,
                                    errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                                    errmsg("cannot delete from view \"%s\"",
                                           RelationGetRelationName(view)),
                                    detail ? errdetail_internal("%s", _(detail)) : 0,
                                    errhint("To enable deleting from the view using MERGE, provide an INSTEAD OF DELETE trigger."));
                        break;
                    case CMD_NOTHING:
                        break;
                    default:
                        elog(ERROR, "unrecognized commandType: %d", action->commandType);
                        break;
                }
            }
            break;
        default:
            elog(ERROR, "unrecognized CmdType: %d", (int) command);
            break;
    }
}

References _, CMD_DELETE, CMD_INSERT, CMD_MERGE, CMD_NOTHING, CMD_UPDATE, elog, ereport, errcode(), errdetail_internal(), errhint(), errmsg, ERROR, fb(), foreach_node, RelationGetRelationName, and RelationData::trigdesc.

Referenced by CheckValidResultRel(), RewriteQuery(), and rewriteTargetView().

expand_generated_columns_in_expr()

Node * expand_generated_columns_in_expr	(	Node *	node,
		Relation	rel,
		int	rt_index
	)

Definition at line 4593 of file rewriteHandler.c.

{
    TupleDesc   tupdesc = RelationGetDescr(rel);
 
    if (tupdesc->constr && tupdesc->constr->has_generated_virtual)
    {
        RangeTblEntry *rte;
 
        rte = makeNode(RangeTblEntry);
        /* eref needs to be set, but the actual name doesn't matter */
        rte->eref = makeAlias(RelationGetRelationName(rel), NIL);
        rte->rtekind = RTE_RELATION;
        rte->relid = RelationGetRelid(rel);
 
        node = expand_generated_columns_internal(node, rel, rt_index, rte, 0);
    }
 
    return node;
}

References TupleDescData::constr, expand_generated_columns_internal(), fb(), TupleConstr::has_generated_virtual, makeAlias(), makeNode, NIL, RelationGetDescr, RelationGetRelationName, RelationGetRelid, and RTE_RELATION.

Referenced by ATExecAlterCheckConstrEnforceability(), ATPrepAlterColumnType(), ATRewriteTable(), createTableConstraints(), ExecRelCheck(), fetch_statentries_for_relation(), get_relation_constraints(), get_relation_statistics(), pgoutput_row_filter_init(), QueueCheckConstraintValidation(), TransformPubWhereClauses(), and TriggerEnabled().

expand_generated_columns_internal()

static Node * expand_generated_columns_internal ( Node *  node, Relation  rel, int  rt_index, RangeTblEntry *  rte, int  result_relation  )

static

Definition at line 4548 of file rewriteHandler.c.

{
    TupleDesc   tupdesc;
 
    tupdesc = RelationGetDescr(rel);
    if (tupdesc->constr && tupdesc->constr->has_generated_virtual)
    {
        List       *tlist = NIL;
 
        for (int i = 0; i < tupdesc->natts; i++)
        {
            Form_pg_attribute attr = TupleDescAttr(tupdesc, i);
 
            if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL)
            {
                Node       *defexpr;
                TargetEntry *te;
 
                defexpr = build_generation_expression(rel, i + 1);
                ChangeVarNodes(defexpr, 1, rt_index, 0);
 
                te = makeTargetEntry((Expr *) defexpr, i + 1, 0, false);
                tlist = lappend(tlist, te);
            }
        }
 
        Assert(list_length(tlist) > 0);
 
        node = ReplaceVarsFromTargetList(node, rt_index, 0, rte, tlist,
                                         result_relation,
                                         REPLACEVARS_CHANGE_VARNO, rt_index,
                                         NULL);
    }
 
    return node;
}

References Assert, build_generation_expression(), ChangeVarNodes(), TupleDescData::constr, fb(), TupleConstr::has_generated_virtual, i, lappend(), list_length(), makeTargetEntry(), TupleDescData::natts, NIL, RelationGetDescr, REPLACEVARS_CHANGE_VARNO, ReplaceVarsFromTargetList(), and TupleDescAttr().

Referenced by expand_generated_columns_in_expr().

findDefaultOnlyColumns()

static Bitmapset * findDefaultOnlyColumns ( RangeTblEntry *  rte )

static

Definition at line 1343 of file rewriteHandler.c.

{
    Bitmapset  *default_only_cols = NULL;
    ListCell   *lc;
 
    foreach(lc, rte->values_lists)
    {
        List       *sublist = (List *) lfirst(lc);
        ListCell   *lc2;
        int         i;
 
        if (default_only_cols == NULL)
        {
            /* Populate the initial result bitmap from the first row */
            i = 0;
            foreach(lc2, sublist)
            {
                Node       *col = (Node *) lfirst(lc2);
 
                i++;
                if (IsA(col, SetToDefault))
                    default_only_cols = bms_add_member(default_only_cols, i);
            }
        }
        else
        {
            /* Update the result bitmap from this next row */
            i = 0;
            foreach(lc2, sublist)
            {
                Node       *col = (Node *) lfirst(lc2);
 
                i++;
                if (!IsA(col, SetToDefault))
                    default_only_cols = bms_del_member(default_only_cols, i);
            }
        }
 
        /*
         * If no column in the rows read so far contains only DEFAULT items,
         * we are done.
         */
        if (bms_is_empty(default_only_cols))
            break;
    }
 
    return default_only_cols;
}

References bms_add_member(), bms_del_member(), bms_is_empty, fb(), i, IsA, and lfirst.

Referenced by rewriteTargetListIU().

fireRIRonSubLink()

static bool fireRIRonSubLink ( Node *  node, fireRIRonSubLink_context *  context  )

static

Definition at line 1973 of file rewriteHandler.c.

{
    if (node == NULL)
        return false;
    if (IsA(node, SubLink))
    {
        SubLink    *sub = (SubLink *) node;
 
        /* Do what we came for */
        sub->subselect = (Node *) fireRIRrules((Query *) sub->subselect,
                                               context->activeRIRs);
 
        /*
         * Remember if any of the sublinks have row security.
         */
        context->hasRowSecurity |= ((Query *) sub->subselect)->hasRowSecurity;
 
        /* Fall through to process lefthand args of SubLink */
    }
 
    /*
     * Do NOT recurse into Query nodes, because fireRIRrules already processed
     * subselects of subselects for us.
     */
    return expression_tree_walker(node, fireRIRonSubLink, context);
}

References fireRIRonSubLink_context::activeRIRs, expression_tree_walker, fb(), fireRIRonSubLink(), fireRIRrules(), fireRIRonSubLink_context::hasRowSecurity, IsA, and SubLink::subselect.

Referenced by fireRIRonSubLink(), and fireRIRrules().

fireRIRrules()

static Query * fireRIRrules ( Query *  parsetree, List *  activeRIRs  )

static

Definition at line 2009 of file rewriteHandler.c.

{
    int         origResultRelation = parsetree->resultRelation;
    int         rt_index;
    ListCell   *lc;
 
    /*
     * Expand SEARCH and CYCLE clauses in CTEs.
     *
     * This is just a convenient place to do this, since we are already
     * looking at each Query.
     */
    foreach(lc, parsetree->cteList)
    {
        CommonTableExpr *cte = lfirst_node(CommonTableExpr, lc);
 
        if (cte->search_clause || cte->cycle_clause)
        {
            cte = rewriteSearchAndCycle(cte);
            lfirst(lc) = cte;
        }
    }
 
    /*
     * don't try to convert this into a foreach loop, because rtable list can
     * get changed each time through...
     */
    rt_index = 0;
    while (rt_index < list_length(parsetree->rtable))
    {
        RangeTblEntry *rte;
        Relation    rel;
        List       *locks;
        RuleLock   *rules;
        RewriteRule *rule;
        int         i;
 
        ++rt_index;
 
        rte = rt_fetch(rt_index, parsetree->rtable);
 
        /*
         * Convert GRAPH_TABLE clause into a subquery using relational
         * operators.  (This will change the rtekind to subquery, so it must
         * be done before the subquery handling below.)
         */
        if (rte->rtekind == RTE_GRAPH_TABLE)
        {
            parsetree = rewriteGraphTable(parsetree, rt_index);
        }
 
        /*
         * A subquery RTE can't have associated rules, so there's nothing to
         * do to this level of the query, but we must recurse into the
         * subquery to expand any rule references in it.
         */
        if (rte->rtekind == RTE_SUBQUERY)
        {
            rte->subquery = fireRIRrules(rte->subquery, activeRIRs);
 
            /*
             * While we are here, make sure the query is marked as having row
             * security if any of its subqueries do.
             */
            parsetree->hasRowSecurity |= rte->subquery->hasRowSecurity;
 
            continue;
        }
 
        /*
         * Joins and other non-relation RTEs can be ignored completely.
         */
        if (rte->rtekind != RTE_RELATION)
            continue;
 
        /*
         * Always ignore RIR rules for materialized views referenced in
         * queries.  (This does not prevent refreshing MVs, since they aren't
         * referenced in their own query definitions.)
         *
         * Note: in the future we might want to allow MVs to be conditionally
         * expanded as if they were regular views, if they are not scannable.
         * In that case this test would need to be postponed till after we've
         * opened the rel, so that we could check its state.
         */
        if (rte->relkind == RELKIND_MATVIEW)
            continue;
 
        /*
         * In INSERT ... ON CONFLICT, ignore the EXCLUDED pseudo-relation;
         * even if it points to a view, we needn't expand it, and should not
         * because we want the RTE to remain of RTE_RELATION type.  Otherwise,
         * it would get changed to RTE_SUBQUERY type, which is an
         * untested/unsupported situation.
         */
        if (parsetree->onConflict &&
            rt_index == parsetree->onConflict->exclRelIndex)
            continue;
 
        /*
         * If the table is not referenced in the query, then we ignore it.
         * This prevents infinite expansion loop due to new rtable entries
         * inserted by expansion of a rule. A table is referenced if it is
         * part of the join set (a source table), or is referenced by any Var
         * nodes, or is the result table.
         */
        if (rt_index != parsetree->resultRelation &&
            !rangeTableEntry_used((Node *) parsetree, rt_index, 0))
            continue;
 
        /*
         * Also, if this is a new result relation introduced by
         * ApplyRetrieveRule, we don't want to do anything more with it.
         */
        if (rt_index == parsetree->resultRelation &&
            rt_index != origResultRelation)
            continue;
 
        /*
         * We can use NoLock here since either the parser or
         * AcquireRewriteLocks should have locked the rel already.
         */
        rel = relation_open(rte->relid, NoLock);
 
        /*
         * Collect the RIR rules that we must apply
         */
        rules = rel->rd_rules;
        if (rules != NULL)
        {
            locks = NIL;
            for (i = 0; i < rules->numLocks; i++)
            {
                rule = rules->rules[i];
                if (rule->event != CMD_SELECT)
                    continue;
 
                locks = lappend(locks, rule);
            }
 
            /*
             * If we found any, apply them --- but first check for recursion!
             */
            if (locks != NIL)
            {
                ListCell   *l;
 
                if (list_member_oid(activeRIRs, RelationGetRelid(rel)))
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                             errmsg("infinite recursion detected in rules for relation \"%s\"",
                                    RelationGetRelationName(rel))));
                activeRIRs = lappend_oid(activeRIRs, RelationGetRelid(rel));
 
                foreach(l, locks)
                {
                    rule = lfirst(l);
 
                    parsetree = ApplyRetrieveRule(parsetree,
                                                  rule,
                                                  rt_index,
                                                  rel,
                                                  activeRIRs);
                }
 
                activeRIRs = list_delete_last(activeRIRs);
            }
        }
 
        table_close(rel, NoLock);
    }
 
    /* Recurse into subqueries in WITH */
    foreach(lc, parsetree->cteList)
    {
        CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
 
        cte->ctequery = (Node *)
            fireRIRrules((Query *) cte->ctequery, activeRIRs);
 
        /*
         * While we are here, make sure the query is marked as having row
         * security if any of its CTEs do.
         */
        parsetree->hasRowSecurity |= ((Query *) cte->ctequery)->hasRowSecurity;
    }
 
    /*
     * Recurse into sublink subqueries, too.  But we already did the ones in
     * the rtable and cteList.
     */
    if (parsetree->hasSubLinks)
    {
        fireRIRonSubLink_context context;
 
        context.activeRIRs = activeRIRs;
        context.hasRowSecurity = false;
 
        query_tree_walker(parsetree, fireRIRonSubLink, &context,
                          QTW_IGNORE_RC_SUBQUERIES);
 
        /*
         * Make sure the query is marked as having row security if any of its
         * sublinks do.
         */
        parsetree->hasRowSecurity |= context.hasRowSecurity;
    }
 
    /*
     * Apply any row-level security policies.  We do this last because it
     * requires special recursion detection if the new quals have sublink
     * subqueries, and if we did it in the loop above query_tree_walker would
     * then recurse into those quals a second time.
     */
    rt_index = 0;
    foreach(lc, parsetree->rtable)
    {
        RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
        Relation    rel;
        List       *securityQuals;
        List       *withCheckOptions;
        bool        hasRowSecurity;
        bool        hasSubLinks;
 
        ++rt_index;
 
        /* Only normal relations can have RLS policies */
        if (rte->rtekind != RTE_RELATION ||
            (rte->relkind != RELKIND_RELATION &&
             rte->relkind != RELKIND_PARTITIONED_TABLE))
            continue;
 
        rel = relation_open(rte->relid, NoLock);
 
        /*
         * Fetch any new security quals that must be applied to this RTE.
         */
        get_row_security_policies(parsetree, rte, rt_index,
                                  &securityQuals, &withCheckOptions,
                                  &hasRowSecurity, &hasSubLinks);
 
        if (securityQuals != NIL || withCheckOptions != NIL)
        {
            if (hasSubLinks)
            {
                acquireLocksOnSubLinks_context context;
                fireRIRonSubLink_context fire_context;
 
                /*
                 * Recursively process the new quals, checking for infinite
                 * recursion.
                 */
                if (list_member_oid(activeRIRs, RelationGetRelid(rel)))
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                             errmsg("infinite recursion detected in policy for relation \"%s\"",
                                    RelationGetRelationName(rel))));
 
                activeRIRs = lappend_oid(activeRIRs, RelationGetRelid(rel));
 
                /*
                 * get_row_security_policies just passed back securityQuals
                 * and/or withCheckOptions, and there were SubLinks, make sure
                 * we lock any relations which are referenced.
                 *
                 * These locks would normally be acquired by the parser, but
                 * securityQuals and withCheckOptions are added post-parsing.
                 */
                context.for_execute = true;
                (void) acquireLocksOnSubLinks((Node *) securityQuals, &context);
                (void) acquireLocksOnSubLinks((Node *) withCheckOptions,
                                              &context);
 
                /*
                 * Now that we have the locks on anything added by
                 * get_row_security_policies, fire any RIR rules for them.
                 */
                fire_context.activeRIRs = activeRIRs;
                fire_context.hasRowSecurity = false;
 
                expression_tree_walker((Node *) securityQuals,
                                       fireRIRonSubLink, &fire_context);
 
                expression_tree_walker((Node *) withCheckOptions,
                                       fireRIRonSubLink, &fire_context);
 
                /*
                 * We can ignore the value of fire_context.hasRowSecurity
                 * since we only reach this code in cases where hasRowSecurity
                 * is already true.
                 */
                Assert(hasRowSecurity);
 
                activeRIRs = list_delete_last(activeRIRs);
            }
 
            /*
             * Add the new security barrier quals to the start of the RTE's
             * list so that they get applied before any existing barrier quals
             * (which would have come from a security-barrier view, and should
             * get lower priority than RLS conditions on the table itself).
             */
            rte->securityQuals = list_concat(securityQuals,
                                             rte->securityQuals);
 
            parsetree->withCheckOptions = list_concat(withCheckOptions,
                                                      parsetree->withCheckOptions);
        }
 
        /*
         * Make sure the query is marked correctly if row-level security
         * applies, or if the new quals had sublinks.
         */
        if (hasRowSecurity)
            parsetree->hasRowSecurity = true;
        if (hasSubLinks)
            parsetree->hasSubLinks = true;
 
        table_close(rel, NoLock);
    }
 
    return parsetree;
}

References acquireLocksOnSubLinks(), fireRIRonSubLink_context::activeRIRs, ApplyRetrieveRule(), Assert, CMD_SELECT, Query::cteList, CommonTableExpr::ctequery, ereport, errcode(), errmsg, ERROR, OnConflictExpr::exclRelIndex, expression_tree_walker, fb(), fireRIRonSubLink(), fireRIRrules(), acquireLocksOnSubLinks_context::for_execute, get_row_security_policies(), fireRIRonSubLink_context::hasRowSecurity, i, lappend(), lappend_oid(), lfirst, lfirst_node, list_concat(), list_delete_last(), list_length(), list_member_oid(), NIL, NoLock, Query::onConflict, QTW_IGNORE_RC_SUBQUERIES, query_tree_walker, rangeTableEntry_used(), RelationData::rd_rules, relation_open(), RelationGetRelationName, RelationGetRelid, rewriteGraphTable(), rewriteSearchAndCycle(), rt_fetch, Query::rtable, RTE_GRAPH_TABLE, RTE_RELATION, RTE_SUBQUERY, rules, and table_close().

Referenced by ApplyRetrieveRule(), fireRIRonSubLink(), fireRIRrules(), and QueryRewrite().

fireRules()

static List * fireRules ( Query *  parsetree, int  rt_index, CmdType  event, List *  locks, bool *  instead_flag, bool *  returning_flag, Query **  qual_product  )

static

Definition at line 2419 of file rewriteHandler.c.

{
    List       *results = NIL;
    ListCell   *l;
 
    foreach(l, locks)
    {
        RewriteRule *rule_lock = (RewriteRule *) lfirst(l);
        Node       *event_qual = rule_lock->qual;
        List       *actions = rule_lock->actions;
        QuerySource qsrc;
        ListCell   *r;
 
        /* Determine correct QuerySource value for actions */
        if (rule_lock->isInstead)
        {
            if (event_qual != NULL)
                qsrc = QSRC_QUAL_INSTEAD_RULE;
            else
            {
                qsrc = QSRC_INSTEAD_RULE;
                *instead_flag = true;   /* report unqualified INSTEAD */
            }
        }
        else
            qsrc = QSRC_NON_INSTEAD_RULE;
 
        if (qsrc == QSRC_QUAL_INSTEAD_RULE)
        {
            /*
             * If there are INSTEAD rules with qualifications, the original
             * query is still performed. But all the negated rule
             * qualifications of the INSTEAD rules are added so it does its
             * actions only in cases where the rule quals of all INSTEAD rules
             * are false. Think of it as the default action in a case. We save
             * this in *qual_product so RewriteQuery() can add it to the query
             * list after we mangled it up enough.
             *
             * If we have already found an unqualified INSTEAD rule, then
             * *qual_product won't be used, so don't bother building it.
             */
            if (!*instead_flag)
            {
                if (*qual_product == NULL)
                    *qual_product = copyObject(parsetree);
                *qual_product = CopyAndAddInvertedQual(*qual_product,
                                                       event_qual,
                                                       rt_index,
                                                       event);
            }
        }
 
        /* Now process the rule's actions and add them to the result list */
        foreach(r, actions)
        {
            Query      *rule_action = lfirst(r);
 
            if (rule_action->commandType == CMD_NOTHING)
                continue;
 
            rule_action = rewriteRuleAction(parsetree, rule_action,
                                            event_qual, rt_index, event,
                                            returning_flag);
 
            rule_action->querySource = qsrc;
            rule_action->canSetTag = false; /* might change later */
 
            results = lappend(results, rule_action);
        }
    }
 
    return results;
}

References CMD_NOTHING, CopyAndAddInvertedQual(), copyObject, fb(), lappend(), lfirst, NIL, QSRC_INSTEAD_RULE, QSRC_NON_INSTEAD_RULE, QSRC_QUAL_INSTEAD_RULE, and rewriteRuleAction().

Referenced by RewriteQuery().

get_assignment_input()

static Node * get_assignment_input ( Node *  node )

static

Definition at line 1217 of file rewriteHandler.c.

{
    if (node == NULL)
        return NULL;
    if (IsA(node, FieldStore))
    {
        FieldStore *fstore = (FieldStore *) node;
 
        return (Node *) fstore->arg;
    }
    else if (IsA(node, SubscriptingRef))
    {
        SubscriptingRef *sbsref = (SubscriptingRef *) node;
 
        if (sbsref->refassgnexpr == NULL)
            return NULL;
 
        return (Node *) sbsref->refexpr;
    }
 
    return NULL;
}

References FieldStore::arg, fb(), IsA, SubscriptingRef::refassgnexpr, and SubscriptingRef::refexpr.

Referenced by process_matched_tle().

get_view_query()

Query * get_view_query

(

Relation

view

)

Definition at line 2510 of file rewriteHandler.c.

{
    int         i;
 
    Assert(view->rd_rel->relkind == RELKIND_VIEW);
 
    for (i = 0; i < view->rd_rules->numLocks; i++)
    {
        RewriteRule *rule = view->rd_rules->rules[i];
 
        if (rule->event == CMD_SELECT)
        {
            /* A _RETURN rule should have only one action */
            if (list_length(rule->actions) != 1)
                elog(ERROR, "invalid _RETURN rule action specification");
 
            return (Query *) linitial(rule->actions);
        }
    }
 
    elog(ERROR, "failed to find _RETURN rule for view");
    return NULL;                /* keep compiler quiet */
}

References Assert, CMD_SELECT, elog, ERROR, fb(), i, linitial, list_length(), RuleLock::numLocks, RelationData::rd_rel, RelationData::rd_rules, and RuleLock::rules.

Referenced by ATExecSetRelOptions(), LockViewRecurse(), relation_is_updatable(), and rewriteTargetView().

markQueryForLocking()

static void markQueryForLocking ( Query *  qry, Node *  jtnode, LockClauseStrength  strength, LockWaitPolicy  waitPolicy, bool  pushedDown  )

static

Definition at line 1909 of file rewriteHandler.c.

{
    if (jtnode == NULL)
        return;
    if (IsA(jtnode, RangeTblRef))
    {
        int         rti = ((RangeTblRef *) jtnode)->rtindex;
        RangeTblEntry *rte = rt_fetch(rti, qry->rtable);
 
        if (rte->rtekind == RTE_RELATION)
        {
            RTEPermissionInfo *perminfo;
 
            applyLockingClause(qry, rti, strength, waitPolicy, pushedDown);
 
            perminfo = getRTEPermissionInfo(qry->rteperminfos, rte);
            perminfo->requiredPerms |= ACL_SELECT_FOR_UPDATE;
        }
        else if (rte->rtekind == RTE_SUBQUERY)
        {
            applyLockingClause(qry, rti, strength, waitPolicy, pushedDown);
            /* FOR UPDATE/SHARE of subquery is propagated to subquery's rels */
            markQueryForLocking(rte->subquery, (Node *) rte->subquery->jointree,
                                strength, waitPolicy, true);
        }
        /* other RTE types are unaffected by FOR UPDATE */
    }
    else if (IsA(jtnode, FromExpr))
    {
        FromExpr   *f = (FromExpr *) jtnode;
        ListCell   *l;
 
        foreach(l, f->fromlist)
            markQueryForLocking(qry, lfirst(l), strength, waitPolicy, pushedDown);
    }
    else if (IsA(jtnode, JoinExpr))
    {
        JoinExpr   *j = (JoinExpr *) jtnode;
 
        markQueryForLocking(qry, j->larg, strength, waitPolicy, pushedDown);
        markQueryForLocking(qry, j->rarg, strength, waitPolicy, pushedDown);
    }
    else
        elog(ERROR, "unrecognized node type: %d",
             (int) nodeTag(jtnode));
}

References ACL_SELECT_FOR_UPDATE, applyLockingClause(), elog, ERROR, fb(), FromExpr::fromlist, getRTEPermissionInfo(), IsA, j, lfirst, markQueryForLocking(), nodeTag, rt_fetch, Query::rtable, RTE_RELATION, and RTE_SUBQUERY.

Referenced by ApplyRetrieveRule(), and markQueryForLocking().

matchLocks()

static List * matchLocks ( CmdType  event, Relation  relation, int  varno, Query *  parsetree, bool *  hasUpdate  )

static

Definition at line 1654 of file rewriteHandler.c.

{
    RuleLock   *rulelocks = relation->rd_rules;
    List       *matching_locks = NIL;
    int         nlocks;
    int         i;
 
    if (rulelocks == NULL)
        return NIL;
 
    if (parsetree->commandType != CMD_SELECT)
    {
        if (parsetree->resultRelation != varno)
            return NIL;
    }
 
    nlocks = rulelocks->numLocks;
 
    for (i = 0; i < nlocks; i++)
    {
        RewriteRule *oneLock = rulelocks->rules[i];
 
        if (oneLock->event == CMD_UPDATE)
            *hasUpdate = true;
 
        /*
         * Suppress ON INSERT/UPDATE/DELETE rules that are disabled or
         * configured to not fire during the current session's replication
         * role. ON SELECT rules will always be applied in order to keep views
         * working even in LOCAL or REPLICA role.
         */
        if (oneLock->event != CMD_SELECT)
        {
            if (SessionReplicationRole == SESSION_REPLICATION_ROLE_REPLICA)
            {
                if (oneLock->enabled == RULE_FIRES_ON_ORIGIN ||
                    oneLock->enabled == RULE_DISABLED)
                    continue;
            }
            else                /* ORIGIN or LOCAL ROLE */
            {
                if (oneLock->enabled == RULE_FIRES_ON_REPLICA ||
                    oneLock->enabled == RULE_DISABLED)
                    continue;
            }
 
            /* Non-SELECT rules are not supported for MERGE */
            if (parsetree->commandType == CMD_MERGE)
                ereport(ERROR,
                        errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                        errmsg("cannot execute MERGE on relation \"%s\"",
                               RelationGetRelationName(relation)),
                        errdetail("MERGE is not supported for relations with rules."));
        }
 
        if (oneLock->event == event)
        {
            if (parsetree->commandType != CMD_SELECT ||
                rangeTableEntry_used((Node *) parsetree, varno, 0))
                matching_locks = lappend(matching_locks, oneLock);
        }
    }
 
    return matching_locks;
}

References CMD_MERGE, CMD_SELECT, CMD_UPDATE, Query::commandType, ereport, errcode(), errdetail(), errmsg, ERROR, fb(), i, lappend(), NIL, rangeTableEntry_used(), RelationData::rd_rules, RelationGetRelationName, RULE_DISABLED, RULE_FIRES_ON_ORIGIN, RULE_FIRES_ON_REPLICA, SESSION_REPLICATION_ROLE_REPLICA, and SessionReplicationRole.

Referenced by RewriteQuery(), and rewriteValuesRTE().

process_matched_tle()

static TargetEntry * process_matched_tle ( TargetEntry *  src_tle, TargetEntry *  prior_tle, const char *  attrName  )

static

Definition at line 1064 of file rewriteHandler.c.

{
    TargetEntry *result;
    CoerceToDomain *coerce_expr = NULL;
    Node       *src_expr;
    Node       *prior_expr;
    Node       *src_input;
    Node       *prior_input;
    Node       *priorbottom;
    Node       *newexpr;
 
    if (prior_tle == NULL)
    {
        /*
         * Normal case where this is the first assignment to the attribute.
         */
        return src_tle;
    }
 
    /*----------
     * Multiple assignments to same attribute.  Allow only if all are
     * FieldStore or SubscriptingRef assignment operations.  This is a bit
     * tricky because what we may actually be looking at is a nest of
     * such nodes; consider
     *      UPDATE tab SET col.fld1.subfld1 = x, col.fld2.subfld2 = y
     * The two expressions produced by the parser will look like
     *      FieldStore(col, fld1, FieldStore(placeholder, subfld1, x))
     *      FieldStore(col, fld2, FieldStore(placeholder, subfld2, y))
     * However, we can ignore the substructure and just consider the top
     * FieldStore or SubscriptingRef from each assignment, because it works to
     * combine these as
     *      FieldStore(FieldStore(col, fld1,
     *                            FieldStore(placeholder, subfld1, x)),
     *                 fld2, FieldStore(placeholder, subfld2, y))
     * Note the leftmost expression goes on the inside so that the
     * assignments appear to occur left-to-right.
     *
     * For FieldStore, instead of nesting we can generate a single
     * FieldStore with multiple target fields.  We must nest when
     * SubscriptingRefs are involved though.
     *
     * As a further complication, the destination column might be a domain,
     * resulting in each assignment containing a CoerceToDomain node over a
     * FieldStore or SubscriptingRef.  These should have matching target
     * domains, so we strip them and reconstitute a single CoerceToDomain over
     * the combined FieldStore/SubscriptingRef nodes.  (Notice that this has
     * the result that the domain's checks are applied only after we do all
     * the field or element updates, not after each one.  This is desirable.)
     *----------
     */
    src_expr = (Node *) src_tle->expr;
    prior_expr = (Node *) prior_tle->expr;
 
    if (src_expr && IsA(src_expr, CoerceToDomain) &&
        prior_expr && IsA(prior_expr, CoerceToDomain) &&
        ((CoerceToDomain *) src_expr)->resulttype ==
        ((CoerceToDomain *) prior_expr)->resulttype)
    {
        /* we assume without checking that resulttypmod/resultcollid match */
        coerce_expr = (CoerceToDomain *) src_expr;
        src_expr = (Node *) ((CoerceToDomain *) src_expr)->arg;
        prior_expr = (Node *) ((CoerceToDomain *) prior_expr)->arg;
    }
 
    src_input = get_assignment_input(src_expr);
    prior_input = get_assignment_input(prior_expr);
    if (src_input == NULL ||
        prior_input == NULL ||
        exprType(src_expr) != exprType(prior_expr))
        ereport(ERROR,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("multiple assignments to same column \"%s\"",
                        attrName)));
 
    /*
     * Prior TLE could be a nest of assignments if we do this more than once.
     */
    priorbottom = prior_input;
    for (;;)
    {
        Node       *newbottom = get_assignment_input(priorbottom);
 
        if (newbottom == NULL)
            break;              /* found the original Var reference */
        priorbottom = newbottom;
    }
    if (!equal(priorbottom, src_input))
        ereport(ERROR,
                (errcode(ERRCODE_SYNTAX_ERROR),
                 errmsg("multiple assignments to same column \"%s\"",
                        attrName)));
 
    /*
     * Looks OK to nest 'em.
     */
    if (IsA(src_expr, FieldStore))
    {
        FieldStore *fstore = makeNode(FieldStore);
 
        if (IsA(prior_expr, FieldStore))
        {
            /* combine the two */
            memcpy(fstore, prior_expr, sizeof(FieldStore));
            fstore->newvals =
                list_concat_copy(((FieldStore *) prior_expr)->newvals,
                                 ((FieldStore *) src_expr)->newvals);
            fstore->fieldnums =
                list_concat_copy(((FieldStore *) prior_expr)->fieldnums,
                                 ((FieldStore *) src_expr)->fieldnums);
        }
        else
        {
            /* general case, just nest 'em */
            memcpy(fstore, src_expr, sizeof(FieldStore));
            fstore->arg = (Expr *) prior_expr;
        }
        newexpr = (Node *) fstore;
    }
    else if (IsA(src_expr, SubscriptingRef))
    {
        SubscriptingRef *sbsref = makeNode(SubscriptingRef);
 
        memcpy(sbsref, src_expr, sizeof(SubscriptingRef));
        sbsref->refexpr = (Expr *) prior_expr;
        newexpr = (Node *) sbsref;
    }
    else
    {
        elog(ERROR, "cannot happen");
        newexpr = NULL;
    }
 
    if (coerce_expr)
    {
        /* put back the CoerceToDomain */
        CoerceToDomain *newcoerce = makeNode(CoerceToDomain);
 
        memcpy(newcoerce, coerce_expr, sizeof(CoerceToDomain));
        newcoerce->arg = (Expr *) newexpr;
        newexpr = (Node *) newcoerce;
    }
 
    result = flatCopyTargetEntry(src_tle);
    result->expr = (Expr *) newexpr;
    return result;
}

References arg, FieldStore::arg, elog, equal(), ereport, errcode(), errmsg, ERROR, exprType(), fb(), flatCopyTargetEntry(), get_assignment_input(), IsA, list_concat_copy(), makeNode, memcpy(), FieldStore::newvals, SubscriptingRef::refexpr, and result.

Referenced by rewriteTargetListIU().

QueryRewrite()

List * QueryRewrite

(

Query *

parsetree

)

Definition at line 4665 of file rewriteHandler.c.

{
    int64       input_query_id = parsetree->queryId;
    List       *querylist;
    List       *results;
    ListCell   *l;
    CmdType     origCmdType;
    bool        foundOriginalQuery;
    Query      *lastInstead;
 
    /*
     * This function is only applied to top-level original queries
     */
    Assert(parsetree->querySource == QSRC_ORIGINAL);
    Assert(parsetree->canSetTag);
 
    /*
     * Step 1
     *
     * Apply all non-SELECT rules possibly getting 0 or many queries
     */
    querylist = RewriteQuery(parsetree, NIL, 0, 0);
 
    /*
     * Step 2
     *
     * Apply all the RIR rules on each query
     *
     * This is also a handy place to mark each query with the original queryId
     */
    results = NIL;
    foreach(l, querylist)
    {
        Query      *query = (Query *) lfirst(l);
 
        query = fireRIRrules(query, NIL);
 
        query->queryId = input_query_id;
 
        results = lappend(results, query);
    }
 
    /*
     * Step 3
     *
     * Determine which, if any, of the resulting queries is supposed to set
     * the command-result tag; and update the canSetTag fields accordingly.
     *
     * If the original query is still in the list, it sets the command tag.
     * Otherwise, the last INSTEAD query of the same kind as the original is
     * allowed to set the tag.  (Note these rules can leave us with no query
     * setting the tag.  The tcop code has to cope with this by setting up a
     * default tag based on the original un-rewritten query.)
     *
     * The Asserts verify that at most one query in the result list is marked
     * canSetTag.  If we aren't checking asserts, we can fall out of the loop
     * as soon as we find the original query.
     */
    origCmdType = parsetree->commandType;
    foundOriginalQuery = false;
    lastInstead = NULL;
 
    foreach(l, results)
    {
        Query      *query = (Query *) lfirst(l);
 
        if (query->querySource == QSRC_ORIGINAL)
        {
            Assert(query->canSetTag);
            Assert(!foundOriginalQuery);
            foundOriginalQuery = true;
#ifndef USE_ASSERT_CHECKING
            break;
#endif
        }
        else
        {
            Assert(!query->canSetTag);
            if (query->commandType == origCmdType &&
                (query->querySource == QSRC_INSTEAD_RULE ||
                 query->querySource == QSRC_QUAL_INSTEAD_RULE))
                lastInstead = query;
        }
    }
 
    if (!foundOriginalQuery && lastInstead != NULL)
        lastInstead->canSetTag = true;
 
    return results;
}

References Assert, Query::commandType, fb(), fireRIRrules(), lappend(), lfirst, NIL, QSRC_INSTEAD_RULE, QSRC_ORIGINAL, QSRC_QUAL_INSTEAD_RULE, and RewriteQuery().

Referenced by ExecCreateTableAs(), ExplainOneUtility(), ExplainQuery(), PerformCursorOpen(), pg_rewrite_query(), and refresh_matview_datafill().

relation_is_updatable()

int relation_is_updatable	(	Oid	reloid,
		List *	outer_reloids,
		bool	include_triggers,
		Bitmapset *	include_cols
	)

Definition at line 2892 of file rewriteHandler.c.

{
    int         events = 0;
    Relation    rel;
    RuleLock   *rulelocks;
 
#define ALL_EVENTS ((1 << CMD_INSERT) | (1 << CMD_UPDATE) | (1 << CMD_DELETE))
 
    /* Since this function recurses, it could be driven to stack overflow */
    check_stack_depth();
 
    rel = try_relation_open(reloid, AccessShareLock);
 
    /*
     * If the relation doesn't exist, return zero rather than throwing an
     * error.  This is helpful since scanning an information_schema view under
     * MVCC rules can result in referencing rels that have actually been
     * deleted already.
     */
    if (rel == NULL)
        return 0;
 
    /* If we detect a recursive view, report that it is not updatable */
    if (list_member_oid(outer_reloids, RelationGetRelid(rel)))
    {
        relation_close(rel, AccessShareLock);
        return 0;
    }
 
    /* If the relation is a table, it is always updatable */
    if (rel->rd_rel->relkind == RELKIND_RELATION ||
        rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
    {
        relation_close(rel, AccessShareLock);
        return ALL_EVENTS;
    }
 
    /* Look for unconditional DO INSTEAD rules, and note supported events */
    rulelocks = rel->rd_rules;
    if (rulelocks != NULL)
    {
        int         i;
 
        for (i = 0; i < rulelocks->numLocks; i++)
        {
            if (rulelocks->rules[i]->isInstead &&
                rulelocks->rules[i]->qual == NULL)
            {
                events |= ((1 << rulelocks->rules[i]->event) & ALL_EVENTS);
            }
        }
 
        /* If we have rules for all events, we're done */
        if (events == ALL_EVENTS)
        {
            relation_close(rel, AccessShareLock);
            return events;
        }
    }
 
    /* Similarly look for INSTEAD OF triggers, if they are to be included */
    if (include_triggers)
    {
        TriggerDesc *trigDesc = rel->trigdesc;
 
        if (trigDesc)
        {
            if (trigDesc->trig_insert_instead_row)
                events |= (1 << CMD_INSERT);
            if (trigDesc->trig_update_instead_row)
                events |= (1 << CMD_UPDATE);
            if (trigDesc->trig_delete_instead_row)
                events |= (1 << CMD_DELETE);
 
            /* If we have triggers for all events, we're done */
            if (events == ALL_EVENTS)
            {
                relation_close(rel, AccessShareLock);
                return events;
            }
        }
    }
 
    /* If this is a foreign table, check which update events it supports */
    if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
    {
        FdwRoutine *fdwroutine = GetFdwRoutineForRelation(rel, false);
 
        if (fdwroutine->IsForeignRelUpdatable != NULL)
            events |= fdwroutine->IsForeignRelUpdatable(rel);
        else
        {
            /* Assume presence of executor functions is sufficient */
            if (fdwroutine->ExecForeignInsert != NULL)
                events |= (1 << CMD_INSERT);
            if (fdwroutine->ExecForeignUpdate != NULL)
                events |= (1 << CMD_UPDATE);
            if (fdwroutine->ExecForeignDelete != NULL)
                events |= (1 << CMD_DELETE);
        }
 
        relation_close(rel, AccessShareLock);
        return events;
    }
 
    /* Check if this is an automatically updatable view */
    if (rel->rd_rel->relkind == RELKIND_VIEW)
    {
        Query      *viewquery = get_view_query(rel);
 
        if (view_query_is_auto_updatable(viewquery, false) == NULL)
        {
            Bitmapset  *updatable_cols;
            int         auto_events;
            RangeTblRef *rtr;
            RangeTblEntry *base_rte;
            Oid         baseoid;
 
            /*
             * Determine which of the view's columns are updatable. If there
             * are none within the set of columns we are looking at, then the
             * view doesn't support INSERT/UPDATE, but it may still support
             * DELETE.
             */
            view_cols_are_auto_updatable(viewquery, NULL,
                                         &updatable_cols, NULL);
 
            if (include_cols != NULL)
                updatable_cols = bms_int_members(updatable_cols, include_cols);
 
            if (bms_is_empty(updatable_cols))
                auto_events = (1 << CMD_DELETE);    /* May support DELETE */
            else
                auto_events = ALL_EVENTS;   /* May support all events */
 
            /*
             * The base relation must also support these update commands.
             * Tables are always updatable, but for any other kind of base
             * relation we must do a recursive check limited to the columns
             * referenced by the locally updatable columns in this view.
             */
            rtr = (RangeTblRef *) linitial(viewquery->jointree->fromlist);
            base_rte = rt_fetch(rtr->rtindex, viewquery->rtable);
            Assert(base_rte->rtekind == RTE_RELATION);
 
            if (base_rte->relkind != RELKIND_RELATION &&
                base_rte->relkind != RELKIND_PARTITIONED_TABLE)
            {
                baseoid = base_rte->relid;
                outer_reloids = lappend_oid(outer_reloids,
                                            RelationGetRelid(rel));
                include_cols = adjust_view_column_set(updatable_cols,
                                                      viewquery->targetList);
                auto_events &= relation_is_updatable(baseoid,
                                                     outer_reloids,
                                                     include_triggers,
                                                     include_cols);
                outer_reloids = list_delete_last(outer_reloids);
            }
            events |= auto_events;
        }
    }
 
    /* If we reach here, the relation may support some update commands */
    relation_close(rel, AccessShareLock);
    return events;
}

References AccessShareLock, adjust_view_column_set(), ALL_EVENTS, Assert, bms_int_members(), bms_is_empty, check_stack_depth(), CMD_DELETE, CMD_INSERT, CMD_UPDATE, FdwRoutine::ExecForeignDelete, FdwRoutine::ExecForeignInsert, FdwRoutine::ExecForeignUpdate, fb(), get_view_query(), GetFdwRoutineForRelation(), i, FdwRoutine::IsForeignRelUpdatable, lappend_oid(), linitial, list_delete_last(), list_member_oid(), RelationData::rd_rel, RelationData::rd_rules, relation_close(), relation_is_updatable(), RelationGetRelid, rt_fetch, RTE_RELATION, RelationData::trigdesc, try_relation_open(), view_cols_are_auto_updatable(), and view_query_is_auto_updatable().

Referenced by pg_column_is_updatable(), pg_relation_is_updatable(), and relation_is_updatable().

RewriteQuery()

static List * RewriteQuery ( Query *  parsetree, List *  rewrite_events, int  orig_rt_length, int  num_ctes_processed  )

static

Definition at line 3932 of file rewriteHandler.c.

{
    CmdType     event = parsetree->commandType;
    bool        instead = false;
    bool        returning = false;
    bool        updatableview = false;
    Query      *qual_product = NULL;
    List       *rewritten = NIL;
    ListCell   *lc1;
 
    /*
     * First, recursively process any insert/update/delete/merge statements in
     * WITH clauses.  (We have to do this first because the WITH clauses may
     * get copied into rule actions below.)
     *
     * Any new WITH clauses from rule actions are processed when we recurse
     * into product queries below.  However, when recursing, we must take care
     * to avoid rewriting a CTE query more than once (because expanding
     * generated columns in the targetlist more than once would fail).  Since
     * new CTEs from product queries are added to the start of the list (see
     * rewriteRuleAction), we just skip the last num_ctes_processed items.
     */
    foreach(lc1, parsetree->cteList)
    {
        CommonTableExpr *cte = lfirst_node(CommonTableExpr, lc1);
        Query      *ctequery = castNode(Query, cte->ctequery);
        int         i = foreach_current_index(lc1);
        List       *newstuff;
 
        /* Skip already-processed CTEs at the end of the list */
        if (i >= list_length(parsetree->cteList) - num_ctes_processed)
            break;
 
        if (ctequery->commandType == CMD_SELECT)
            continue;
 
        newstuff = RewriteQuery(ctequery, rewrite_events, 0, 0);
 
        /*
         * Currently we can only handle unconditional, single-statement DO
         * INSTEAD rules correctly; we have to get exactly one non-utility
         * Query out of the rewrite operation to stuff back into the CTE node.
         */
        if (list_length(newstuff) == 1)
        {
            /* Must check it's not a utility command */
            ctequery = linitial_node(Query, newstuff);
            if (!(ctequery->commandType == CMD_SELECT ||
                  ctequery->commandType == CMD_UPDATE ||
                  ctequery->commandType == CMD_INSERT ||
                  ctequery->commandType == CMD_DELETE ||
                  ctequery->commandType == CMD_MERGE))
            {
                /*
                 * Currently it could only be NOTIFY; this error message will
                 * need work if we ever allow other utility commands in rules.
                 */
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("DO INSTEAD NOTIFY rules are not supported for data-modifying statements in WITH")));
            }
            /* WITH queries should never be canSetTag */
            Assert(!ctequery->canSetTag);
            /* Push the single Query back into the CTE node */
            cte->ctequery = (Node *) ctequery;
        }
        else if (newstuff == NIL)
        {
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("DO INSTEAD NOTHING rules are not supported for data-modifying statements in WITH")));
        }
        else
        {
            ListCell   *lc2;
 
            /* examine queries to determine which error message to issue */
            foreach(lc2, newstuff)
            {
                Query      *q = (Query *) lfirst(lc2);
 
                if (q->querySource == QSRC_QUAL_INSTEAD_RULE)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("conditional DO INSTEAD rules are not supported for data-modifying statements in WITH")));
                if (q->querySource == QSRC_NON_INSTEAD_RULE)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("DO ALSO rules are not supported for data-modifying statements in WITH")));
            }
 
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("multi-statement DO INSTEAD rules are not supported for data-modifying statements in WITH")));
        }
    }
    num_ctes_processed = list_length(parsetree->cteList);
 
    /*
     * If the statement is an insert, update, delete, or merge, adjust its
     * targetlist as needed, and then fire INSERT/UPDATE/DELETE rules on it.
     *
     * SELECT rules are handled later when we have all the queries that should
     * get executed.  Also, utilities aren't rewritten at all (do we still
     * need that check?)
     */
    if (event != CMD_SELECT && event != CMD_UTILITY)
    {
        int         result_relation;
        RangeTblEntry *rt_entry;
        Relation    rt_entry_relation;
        List       *locks;
        int         product_orig_rt_length;
        List       *product_queries;
        bool        hasUpdate = false;
        int         values_rte_index = 0;
        bool        defaults_remaining = false;
 
        result_relation = parsetree->resultRelation;
        Assert(result_relation != 0);
        rt_entry = rt_fetch(result_relation, parsetree->rtable);
        Assert(rt_entry->rtekind == RTE_RELATION);
 
        /*
         * We can use NoLock here since either the parser or
         * AcquireRewriteLocks should have locked the rel already.
         */
        rt_entry_relation = relation_open(rt_entry->relid, NoLock);
 
        /*
         * Rewrite the targetlist as needed for the command type.
         */
        if (event == CMD_INSERT)
        {
            ListCell   *lc2;
            RangeTblEntry *values_rte = NULL;
 
            /*
             * Test if it's a multi-row INSERT ... VALUES (...), (...), ... by
             * looking for a VALUES RTE in the fromlist.  For product queries,
             * we must ignore any already-processed VALUES RTEs from the
             * original query.  These appear at the start of the rangetable.
             */
            foreach(lc2, parsetree->jointree->fromlist)
            {
                RangeTblRef *rtr = (RangeTblRef *) lfirst(lc2);
 
                if (IsA(rtr, RangeTblRef) && rtr->rtindex > orig_rt_length)
                {
                    RangeTblEntry *rte = rt_fetch(rtr->rtindex,
                                                  parsetree->rtable);
 
                    if (rte->rtekind == RTE_VALUES)
                    {
                        /* should not find more than one VALUES RTE */
                        if (values_rte != NULL)
                            elog(ERROR, "more than one VALUES RTE found");
 
                        values_rte = rte;
                        values_rte_index = rtr->rtindex;
                    }
                }
            }
 
            if (values_rte)
            {
                Bitmapset  *unused_values_attrnos = NULL;
 
                /* Process the main targetlist ... */
                parsetree->targetList = rewriteTargetListIU(parsetree->targetList,
                                                            parsetree->commandType,
                                                            parsetree->override,
                                                            rt_entry_relation,
                                                            values_rte,
                                                            values_rte_index,
                                                            &unused_values_attrnos);
                /* ... and the VALUES expression lists */
                if (!rewriteValuesRTE(parsetree, values_rte, values_rte_index,
                                      rt_entry_relation,
                                      unused_values_attrnos))
                    defaults_remaining = true;
            }
            else
            {
                /* Process just the main targetlist */
                parsetree->targetList =
                    rewriteTargetListIU(parsetree->targetList,
                                        parsetree->commandType,
                                        parsetree->override,
                                        rt_entry_relation,
                                        NULL, 0, NULL);
            }
 
            if (parsetree->onConflict &&
                parsetree->onConflict->action == ONCONFLICT_UPDATE)
            {
                parsetree->onConflict->onConflictSet =
                    rewriteTargetListIU(parsetree->onConflict->onConflictSet,
                                        CMD_UPDATE,
                                        parsetree->override,
                                        rt_entry_relation,
                                        NULL, 0, NULL);
            }
        }
        else if (event == CMD_UPDATE)
        {
            Assert(parsetree->override == OVERRIDING_NOT_SET);
 
            if (parsetree->forPortionOf)
            {
                /*
                 * Don't add FOR PORTION OF details until we're done rewriting
                 * a view update, so that we don't add the same qual and TLE
                 * on the recursion.
                 *
                 * Views don't need to do anything special here to remap Vars;
                 * that is handled by the tree walker.
                 */
                if (rt_entry_relation->rd_rel->relkind != RELKIND_VIEW)
                {
                    ListCell   *tl;
 
                    /*
                     * Add qual: UPDATE FOR PORTION OF should be limited to
                     * rows that overlap the target range.
                     */
                    AddQual(parsetree, parsetree->forPortionOf->overlapsExpr);
 
                    /* Update FOR PORTION OF column(s) automatically. */
                    foreach(tl, parsetree->forPortionOf->rangeTargetList)
                    {
                        TargetEntry *tle = (TargetEntry *) lfirst(tl);
 
                        parsetree->targetList = lappend(parsetree->targetList, tle);
                    }
                }
            }
 
            parsetree->targetList =
                rewriteTargetListIU(parsetree->targetList,
                                    parsetree->commandType,
                                    parsetree->override,
                                    rt_entry_relation,
                                    NULL, 0, NULL);
        }
        else if (event == CMD_MERGE)
        {
            Assert(parsetree->override == OVERRIDING_NOT_SET);
 
            /*
             * Rewrite each action targetlist separately
             */
            foreach(lc1, parsetree->mergeActionList)
            {
                MergeAction *action = (MergeAction *) lfirst(lc1);
 
                switch (action->commandType)
                {
                    case CMD_NOTHING:
                    case CMD_DELETE:    /* Nothing to do here */
                        break;
                    case CMD_UPDATE:
                    case CMD_INSERT:
 
                        /*
                         * MERGE actions do not permit multi-row INSERTs, so
                         * there is no VALUES RTE to deal with here.
                         */
                        action->targetList =
                            rewriteTargetListIU(action->targetList,
                                                action->commandType,
                                                action->override,
                                                rt_entry_relation,
                                                NULL, 0, NULL);
                        break;
                    default:
                        elog(ERROR, "unrecognized commandType: %d", action->commandType);
                        break;
                }
            }
        }
        else if (event == CMD_DELETE)
        {
            if (parsetree->forPortionOf)
            {
                /*
                 * Don't add FOR PORTION OF details until we're done rewriting
                 * a view delete, so that we don't add the same qual on the
                 * recursion.
                 *
                 * Views don't need to do anything special here to remap Vars;
                 * that is handled by the tree walker.
                 */
                if (rt_entry_relation->rd_rel->relkind != RELKIND_VIEW)
                {
                    /*
                     * Add qual: DELETE FOR PORTION OF should be limited to
                     * rows that overlap the target range.
                     */
                    AddQual(parsetree, parsetree->forPortionOf->overlapsExpr);
                }
            }
        }
        else
            elog(ERROR, "unrecognized commandType: %d", (int) event);
 
        /*
         * Collect and apply the appropriate rules.
         */
        locks = matchLocks(event, rt_entry_relation,
                           result_relation, parsetree, &hasUpdate);
 
        product_orig_rt_length = list_length(parsetree->rtable);
        product_queries = fireRules(parsetree,
                                    result_relation,
                                    event,
                                    locks,
                                    &instead,
                                    &returning,
                                    &qual_product);
 
        /*
         * If we have a VALUES RTE with any remaining untouched DEFAULT items,
         * and we got any product queries, finalize the VALUES RTE for each
         * product query (replacing the remaining DEFAULT items with NULLs).
         * We don't do this for the original query, because we know that it
         * must be an auto-insert on a view, and so should use the base
         * relation's defaults for any remaining DEFAULT items.
         */
        if (defaults_remaining && product_queries != NIL)
        {
            ListCell   *n;
 
            /*
             * Each product query has its own copy of the VALUES RTE at the
             * same index in the rangetable, so we must finalize each one.
             *
             * Note that if the product query is an INSERT ... SELECT, then
             * the VALUES RTE will be at the same index in the SELECT part of
             * the product query rather than the top-level product query
             * itself.
             */
            foreach(n, product_queries)
            {
                Query      *pt = (Query *) lfirst(n);
                RangeTblEntry *values_rte;
 
                if (pt->commandType == CMD_INSERT &&
                    pt->jointree && IsA(pt->jointree, FromExpr) &&
                    list_length(pt->jointree->fromlist) == 1)
                {
                    Node       *jtnode = (Node *) linitial(pt->jointree->fromlist);
 
                    if (IsA(jtnode, RangeTblRef))
                    {
                        int         rtindex = ((RangeTblRef *) jtnode)->rtindex;
                        RangeTblEntry *src_rte = rt_fetch(rtindex, pt->rtable);
 
                        if (src_rte->rtekind == RTE_SUBQUERY &&
                            src_rte->subquery &&
                            IsA(src_rte->subquery, Query) &&
                            src_rte->subquery->commandType == CMD_SELECT)
                            pt = src_rte->subquery;
                    }
                }
 
                values_rte = rt_fetch(values_rte_index, pt->rtable);
                if (values_rte->rtekind != RTE_VALUES)
                    elog(ERROR, "failed to find VALUES RTE in product query");
 
                rewriteValuesRTEToNulls(pt, values_rte);
            }
        }
 
        /*
         * If there was no unqualified INSTEAD rule, and the target relation
         * is a view without any INSTEAD OF triggers, see if the view can be
         * automatically updated.  If so, we perform the necessary query
         * transformation here and add the resulting query to the
         * product_queries list, so that it gets recursively rewritten if
         * necessary.  For MERGE, the view must be automatically updatable if
         * any of the merge actions lack a corresponding INSTEAD OF trigger.
         *
         * If the view cannot be automatically updated, we throw an error here
         * which is OK since the query would fail at runtime anyway.  Throwing
         * the error here is preferable to the executor check since we have
         * more detailed information available about why the view isn't
         * updatable.
         */
        if (!instead &&
            rt_entry_relation->rd_rel->relkind == RELKIND_VIEW &&
            !view_has_instead_trigger(rt_entry_relation, event,
                                      parsetree->mergeActionList))
        {
            /*
             * If there were any qualified INSTEAD rules, don't allow the view
             * to be automatically updated (an unqualified INSTEAD rule or
             * INSTEAD OF trigger is required).
             */
            if (qual_product != NULL)
                error_view_not_updatable(rt_entry_relation,
                                         parsetree->commandType,
                                         parsetree->mergeActionList,
                                         gettext_noop("Views with conditional DO INSTEAD rules are not automatically updatable."));
 
            /*
             * Attempt to rewrite the query to automatically update the view.
             * This throws an error if the view can't be automatically
             * updated.
             */
            parsetree = rewriteTargetView(parsetree, rt_entry_relation);
 
            /*
             * At this point product_queries contains any DO ALSO rule
             * actions. Add the rewritten query before or after those.  This
             * must match the handling the original query would have gotten
             * below, if we allowed it to be included again.
             */
            if (parsetree->commandType == CMD_INSERT)
                product_queries = lcons(parsetree, product_queries);
            else
                product_queries = lappend(product_queries, parsetree);
 
            /*
             * Set the "instead" flag, as if there had been an unqualified
             * INSTEAD, to prevent the original query from being included a
             * second time below.  The transformation will have rewritten any
             * RETURNING list, so we can also set "returning" to forestall
             * throwing an error below.
             */
            instead = true;
            returning = true;
            updatableview = true;
        }
 
        /*
         * If we got any product queries, recursively rewrite them --- but
         * first check for recursion!
         */
        if (product_queries != NIL)
        {
            ListCell   *n;
            rewrite_event *rev;
 
            foreach(n, rewrite_events)
            {
                rev = (rewrite_event *) lfirst(n);
                if (rev->relation == RelationGetRelid(rt_entry_relation) &&
                    rev->event == event)
                    ereport(ERROR,
                            (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                             errmsg("infinite recursion detected in rules for relation \"%s\"",
                                    RelationGetRelationName(rt_entry_relation))));
            }
 
            rev = palloc_object(rewrite_event);
            rev->relation = RelationGetRelid(rt_entry_relation);
            rev->event = event;
            rewrite_events = lappend(rewrite_events, rev);
 
            foreach(n, product_queries)
            {
                Query      *pt = (Query *) lfirst(n);
                List       *newstuff;
 
                /*
                 * For an updatable view, pt might be the rewritten version of
                 * the original query, in which case we pass on orig_rt_length
                 * to finish processing any VALUES RTE it contained.
                 *
                 * Otherwise, we have a product query created by fireRules().
                 * Any VALUES RTEs from the original query have been fully
                 * processed, and must be skipped when we recurse.
                 */
                newstuff = RewriteQuery(pt, rewrite_events,
                                        pt == parsetree ?
                                        orig_rt_length :
                                        product_orig_rt_length,
                                        num_ctes_processed);
                rewritten = list_concat(rewritten, newstuff);
            }
 
            rewrite_events = list_delete_last(rewrite_events);
        }
 
        /*
         * If there is an INSTEAD, and the original query has a RETURNING, we
         * have to have found a RETURNING in the rule(s), else fail. (Because
         * DefineQueryRewrite only allows RETURNING in unconditional INSTEAD
         * rules, there's no need to worry whether the substituted RETURNING
         * will actually be executed --- it must be.)
         */
        if ((instead || qual_product != NULL) &&
            parsetree->returningList &&
            !returning)
        {
            switch (event)
            {
                case CMD_INSERT:
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot perform INSERT RETURNING on relation \"%s\"",
                                    RelationGetRelationName(rt_entry_relation)),
                             errhint("You need an unconditional ON INSERT DO INSTEAD rule with a RETURNING clause.")));
                    break;
                case CMD_UPDATE:
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot perform UPDATE RETURNING on relation \"%s\"",
                                    RelationGetRelationName(rt_entry_relation)),
                             errhint("You need an unconditional ON UPDATE DO INSTEAD rule with a RETURNING clause.")));
                    break;
                case CMD_DELETE:
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot perform DELETE RETURNING on relation \"%s\"",
                                    RelationGetRelationName(rt_entry_relation)),
                             errhint("You need an unconditional ON DELETE DO INSTEAD rule with a RETURNING clause.")));
                    break;
                default:
                    elog(ERROR, "unrecognized commandType: %d",
                         (int) event);
                    break;
            }
        }
 
        /*
         * Updatable views are supported by ON CONFLICT, so don't prevent that
         * case from proceeding
         */
        if (parsetree->onConflict &&
            (product_queries != NIL || hasUpdate) &&
            !updatableview)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("INSERT with ON CONFLICT clause cannot be used with table that has INSERT or UPDATE rules")));
 
        table_close(rt_entry_relation, NoLock);
    }
 
    /*
     * For INSERTs, the original query is done first; for UPDATE/DELETE, it is
     * done last.  This is needed because update and delete rule actions might
     * not do anything if they are invoked after the update or delete is
     * performed. The command counter increment between the query executions
     * makes the deleted (and maybe the updated) tuples disappear so the scans
     * for them in the rule actions cannot find them.
     *
     * If we found any unqualified INSTEAD, the original query is not done at
     * all, in any form.  Otherwise, we add the modified form if qualified
     * INSTEADs were found, else the unmodified form.
     */
    if (!instead)
    {
        if (parsetree->commandType == CMD_INSERT)
        {
            if (qual_product != NULL)
                rewritten = lcons(qual_product, rewritten);
            else
                rewritten = lcons(parsetree, rewritten);
        }
        else
        {
            if (qual_product != NULL)
                rewritten = lappend(rewritten, qual_product);
            else
                rewritten = lappend(rewritten, parsetree);
        }
    }
 
    /*
     * If the original query has a CTE list, and we generated more than one
     * non-utility result query, we have to fail because we'll have copied the
     * CTE list into each result query.  That would break the expectation of
     * single evaluation of CTEs.  This could possibly be fixed by
     * restructuring so that a CTE list can be shared across multiple Query
     * and PlannableStatement nodes.
     */
    if (parsetree->cteList != NIL)
    {
        int         qcount = 0;
 
        foreach(lc1, rewritten)
        {
            Query      *q = (Query *) lfirst(lc1);
 
            if (q->commandType != CMD_UTILITY)
                qcount++;
        }
        if (qcount > 1)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("WITH cannot be used in a query that is rewritten by rules into multiple queries")));
    }
 
    return rewritten;
}

References OnConflictExpr::action, AddQual(), Assert, castNode, CMD_DELETE, CMD_INSERT, CMD_MERGE, CMD_NOTHING, CMD_SELECT, CMD_UPDATE, CMD_UTILITY, Query::commandType, Query::cteList, CommonTableExpr::ctequery, elog, ereport, errcode(), errhint(), errmsg, ERROR, error_view_not_updatable(), fb(), fireRules(), foreach_current_index, Query::forPortionOf, FromExpr::fromlist, gettext_noop, i, IsA, Query::jointree, lappend(), lcons(), lfirst, lfirst_node, linitial, linitial_node, list_concat(), list_delete_last(), list_length(), matchLocks(), Query::mergeActionList, NIL, NoLock, Query::onConflict, ONCONFLICT_UPDATE, OnConflictExpr::onConflictSet, ForPortionOfExpr::overlapsExpr, OVERRIDING_NOT_SET, palloc_object, QSRC_NON_INSTEAD_RULE, QSRC_QUAL_INSTEAD_RULE, ForPortionOfExpr::rangeTargetList, relation_open(), RelationGetRelationName, RelationGetRelid, Query::returningList, RewriteQuery(), rewriteTargetListIU(), rewriteTargetView(), rewriteValuesRTE(), rewriteValuesRTEToNulls(), rt_fetch, Query::rtable, RTE_RELATION, RTE_SUBQUERY, RTE_VALUES, table_close(), Query::targetList, and view_has_instead_trigger().

Referenced by QueryRewrite(), and RewriteQuery().

rewriteRuleAction()

static Query * rewriteRuleAction ( Query *  parsetree, Query *  rule_action, Node *  rule_qual, int  rt_index, CmdType  event, bool *  returning_flag  )

static

Definition at line 353 of file rewriteHandler.c.

{
    int         current_varno,
                new_varno;
    int         rt_length;
    Query      *sub_action;
    Query     **sub_action_ptr;
    acquireLocksOnSubLinks_context context;
    ListCell   *lc;
 
    context.for_execute = true;
 
    /*
     * Make modifiable copies of rule action and qual (what we're passed are
     * the stored versions in the relcache; don't touch 'em!).
     */
    rule_action = copyObject(rule_action);
    rule_qual = copyObject(rule_qual);
 
    /*
     * Acquire necessary locks and fix any deleted JOIN RTE entries.
     */
    AcquireRewriteLocks(rule_action, true, false);
    (void) acquireLocksOnSubLinks(rule_qual, &context);
 
    current_varno = rt_index;
    rt_length = list_length(parsetree->rtable);
    new_varno = PRS2_NEW_VARNO + rt_length;
 
    /*
     * Adjust rule action and qual to offset its varnos, so that we can merge
     * its rtable with the main parsetree's rtable.
     *
     * If the rule action is an INSERT...SELECT, the OLD/NEW rtable entries
     * will be in the SELECT part, and we have to modify that rather than the
     * top-level INSERT (kluge!).
     */
    sub_action = getInsertSelectQuery(rule_action, &sub_action_ptr);
 
    OffsetVarNodes((Node *) sub_action, rt_length, 0);
    OffsetVarNodes(rule_qual, rt_length, 0);
    /* but references to OLD should point at original rt_index */
    ChangeVarNodes((Node *) sub_action,
                   PRS2_OLD_VARNO + rt_length, rt_index, 0);
    ChangeVarNodes(rule_qual,
                   PRS2_OLD_VARNO + rt_length, rt_index, 0);
 
    /*
     * Mark any subquery RTEs in the rule action as LATERAL if they contain
     * Vars referring to the current query level (references to NEW/OLD).
     * Those really are lateral references, but we've historically not
     * required users to mark such subqueries with LATERAL explicitly.  But
     * the planner will complain if such Vars exist in a non-LATERAL subquery,
     * so we have to fix things up here.
     */
    foreach(lc, sub_action->rtable)
    {
        RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
 
        if (rte->rtekind == RTE_SUBQUERY && !rte->lateral &&
            contain_vars_of_level((Node *) rte->subquery, 1))
            rte->lateral = true;
    }
 
    /*
     * Generate expanded rtable consisting of main parsetree's rtable plus
     * rule action's rtable; this becomes the complete rtable for the rule
     * action.  Some of the entries may be unused after we finish rewriting,
     * but we leave them all in place to avoid having to adjust the query's
     * varnos.  RT entries that are not referenced in the completed jointree
     * will be ignored by the planner, so they do not affect query semantics.
     *
     * Also merge RTEPermissionInfo lists to ensure that all permissions are
     * checked correctly.
     *
     * If the rule is INSTEAD, then the original query won't be executed at
     * all, and so its rteperminfos must be preserved so that the executor
     * will do the correct permissions checks on the relations referenced in
     * it. This allows us to check that the caller has, say, insert-permission
     * on a view, when the view is not semantically referenced at all in the
     * resulting query.
     *
     * When a rule is not INSTEAD, the permissions checks done using the
     * copied entries will be redundant with those done during execution of
     * the original query, but we don't bother to treat that case differently.
     *
     * NOTE: because planner will destructively alter rtable and rteperminfos,
     * we must ensure that rule action's lists are separate and shares no
     * substructure with the main query's lists.  Hence do a deep copy here
     * for both.
     */
    {
        List       *rtable_tail = sub_action->rtable;
        List       *perminfos_tail = sub_action->rteperminfos;
 
        /*
         * RewriteQuery relies on the fact that RT entries from the original
         * query appear at the start of the expanded rtable, so we put the
         * action's original table at the end of the list.
         */
        sub_action->rtable = copyObject(parsetree->rtable);
        sub_action->rteperminfos = copyObject(parsetree->rteperminfos);
        CombineRangeTables(&sub_action->rtable, &sub_action->rteperminfos,
                           rtable_tail, perminfos_tail);
    }
 
    /*
     * There could have been some SubLinks in parsetree's rtable, in which
     * case we'd better mark the sub_action correctly.
     */
    if (parsetree->hasSubLinks && !sub_action->hasSubLinks)
    {
        foreach(lc, parsetree->rtable)
        {
            RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
 
            switch (rte->rtekind)
            {
                case RTE_RELATION:
                    sub_action->hasSubLinks =
                        checkExprHasSubLink((Node *) rte->tablesample);
                    break;
                case RTE_FUNCTION:
                    sub_action->hasSubLinks =
                        checkExprHasSubLink((Node *) rte->functions);
                    break;
                case RTE_TABLEFUNC:
                    sub_action->hasSubLinks =
                        checkExprHasSubLink((Node *) rte->tablefunc);
                    break;
                case RTE_VALUES:
                    sub_action->hasSubLinks =
                        checkExprHasSubLink((Node *) rte->values_lists);
                    break;
                default:
                    /* other RTE types don't contain bare expressions */
                    break;
            }
            sub_action->hasSubLinks |=
                checkExprHasSubLink((Node *) rte->securityQuals);
            if (sub_action->hasSubLinks)
                break;          /* no need to keep scanning rtable */
        }
    }
 
    /*
     * Also, we might have absorbed some RTEs with RLS conditions into the
     * sub_action.  If so, mark it as hasRowSecurity, whether or not those
     * RTEs will be referenced after we finish rewriting.  (Note: currently
     * this is a no-op because RLS conditions aren't added till later, but it
     * seems like good future-proofing to do this anyway.)
     */
    sub_action->hasRowSecurity |= parsetree->hasRowSecurity;
 
    /*
     * Each rule action's jointree should be the main parsetree's jointree
     * plus that rule's jointree, but usually *without* the original rtindex
     * that we're replacing (if present, which it won't be for INSERT). Note
     * that if the rule action refers to OLD, its jointree will add a
     * reference to rt_index.  If the rule action doesn't refer to OLD, but
     * either the rule_qual or the user query quals do, then we need to keep
     * the original rtindex in the jointree to provide data for the quals.  We
     * don't want the original rtindex to be joined twice, however, so avoid
     * keeping it if the rule action mentions it.
     *
     * As above, the action's jointree must not share substructure with the
     * main parsetree's.
     */
    if (sub_action->commandType != CMD_UTILITY)
    {
        bool        keeporig;
        List       *newjointree;
 
        Assert(sub_action->jointree != NULL);
        keeporig = (!rangeTableEntry_used((Node *) sub_action->jointree,
                                          rt_index, 0)) &&
            (rangeTableEntry_used(rule_qual, rt_index, 0) ||
             rangeTableEntry_used(parsetree->jointree->quals, rt_index, 0));
        newjointree = adjustJoinTreeList(parsetree, !keeporig, rt_index);
        if (newjointree != NIL)
        {
            /*
             * If sub_action is a setop, manipulating its jointree will do no
             * good at all, because the jointree is dummy.  (Perhaps someday
             * we could push the joining and quals down to the member
             * statements of the setop?)
             */
            if (sub_action->setOperations != NULL)
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented")));
 
            sub_action->jointree->fromlist =
                list_concat(newjointree, sub_action->jointree->fromlist);
 
            /*
             * There could have been some SubLinks in newjointree, in which
             * case we'd better mark the sub_action correctly.
             */
            if (parsetree->hasSubLinks && !sub_action->hasSubLinks)
                sub_action->hasSubLinks =
                    checkExprHasSubLink((Node *) newjointree);
        }
    }
 
    /*
     * If the original query has any CTEs, copy them into the rule action. But
     * we don't need them for a utility action.
     */
    if (parsetree->cteList != NIL && sub_action->commandType != CMD_UTILITY)
    {
        /*
         * Annoying implementation restriction: because CTEs are identified by
         * name within a cteList, we can't merge a CTE from the original query
         * if it has the same name as any CTE in the rule action.
         *
         * This could possibly be fixed by using some sort of internally
         * generated ID, instead of names, to link CTE RTEs to their CTEs.
         * However, decompiling the results would be quite confusing; note the
         * merge of hasRecursive flags below, which could change the apparent
         * semantics of such redundantly-named CTEs.
         */
        foreach(lc, parsetree->cteList)
        {
            CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
            ListCell   *lc2;
 
            foreach(lc2, sub_action->cteList)
            {
                CommonTableExpr *cte2 = (CommonTableExpr *) lfirst(lc2);
 
                if (strcmp(cte->ctename, cte2->ctename) == 0)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("WITH query name \"%s\" appears in both a rule action and the query being rewritten",
                                    cte->ctename)));
            }
        }
 
        /*
         * OK, it's safe to combine the CTE lists.  Beware that RewriteQuery
         * knows we concatenate the lists in this order.
         */
        sub_action->cteList = list_concat(sub_action->cteList,
                                          copyObject(parsetree->cteList));
        /* ... and don't forget about the associated flags */
        sub_action->hasRecursive |= parsetree->hasRecursive;
        sub_action->hasModifyingCTE |= parsetree->hasModifyingCTE;
 
        /*
         * If rule_action is different from sub_action (i.e., the rule action
         * is an INSERT...SELECT), then we might have just added some
         * data-modifying CTEs that are not at the top query level.  This is
         * disallowed by the parser and we mustn't generate such trees here
         * either, so throw an error.
         *
         * Conceivably such cases could be supported by attaching the original
         * query's CTEs to rule_action not sub_action.  But to do that, we'd
         * have to increment ctelevelsup in RTEs and SubLinks copied from the
         * original query.  For now, it doesn't seem worth the trouble.
         */
        if (sub_action->hasModifyingCTE && rule_action != sub_action)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("INSERT ... SELECT rule actions are not supported for queries having data-modifying statements in WITH")));
    }
 
    /*
     * Event Qualification forces copying of parsetree and splitting into two
     * queries one w/rule_qual, one w/NOT rule_qual. Also add user query qual
     * onto rule action
     */
    AddQual(sub_action, rule_qual);
 
    AddQual(sub_action, parsetree->jointree->quals);
 
    /*
     * Rewrite new.attribute with right hand side of target-list entry for
     * appropriate field name in insert/update.
     *
     * KLUGE ALERT: since ReplaceVarsFromTargetList returns a mutated copy, we
     * can't just apply it to sub_action; we have to remember to update the
     * sublink inside rule_action, too.
     */
    if ((event == CMD_INSERT || event == CMD_UPDATE) &&
        sub_action->commandType != CMD_UTILITY)
    {
        sub_action = (Query *)
            ReplaceVarsFromTargetList((Node *) sub_action,
                                      new_varno,
                                      0,
                                      rt_fetch(new_varno, sub_action->rtable),
                                      parsetree->targetList,
                                      sub_action->resultRelation,
                                      (event == CMD_UPDATE) ?
                                      REPLACEVARS_CHANGE_VARNO :
                                      REPLACEVARS_SUBSTITUTE_NULL,
                                      current_varno,
                                      NULL);
        if (sub_action_ptr)
            *sub_action_ptr = sub_action;
        else
            rule_action = sub_action;
    }
 
    /*
     * If rule_action is INSERT .. ON CONFLICT DO SELECT, the parser should
     * have verified that it has a RETURNING clause, but we must also check
     * that the triggering query has a RETURNING clause.
     */
    if (rule_action->onConflict &&
        rule_action->onConflict->action == ONCONFLICT_SELECT &&
        (!rule_action->returningList || !parsetree->returningList))
        ereport(ERROR,
                errcode(ERRCODE_SYNTAX_ERROR),
                errmsg("ON CONFLICT DO SELECT requires a RETURNING clause"),
                errdetail("A rule action is INSERT ... ON CONFLICT DO SELECT, which requires a RETURNING clause."));
 
    /*
     * If rule_action has a RETURNING clause, then either throw it away if the
     * triggering query has no RETURNING clause, or rewrite it to emit what
     * the triggering query's RETURNING clause asks for.  Throw an error if
     * more than one rule has a RETURNING clause.
     */
    if (!parsetree->returningList)
        rule_action->returningList = NIL;
    else if (rule_action->returningList)
    {
        if (*returning_flag)
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("cannot have RETURNING lists in multiple rules")));
        *returning_flag = true;
        rule_action->returningList = (List *)
            ReplaceVarsFromTargetList((Node *) parsetree->returningList,
                                      parsetree->resultRelation,
                                      0,
                                      rt_fetch(parsetree->resultRelation,
                                               parsetree->rtable),
                                      rule_action->returningList,
                                      rule_action->resultRelation,
                                      REPLACEVARS_REPORT_ERROR,
                                      0,
                                      &rule_action->hasSubLinks);
 
        /* use triggering query's aliases for OLD and NEW in RETURNING list */
        rule_action->returningOldAlias = parsetree->returningOldAlias;
        rule_action->returningNewAlias = parsetree->returningNewAlias;
 
        /*
         * There could have been some SubLinks in parsetree's returningList,
         * in which case we'd better mark the rule_action correctly.
         */
        if (parsetree->hasSubLinks && !rule_action->hasSubLinks)
            rule_action->hasSubLinks =
                checkExprHasSubLink((Node *) rule_action->returningList);
    }
 
    return rule_action;
}

References acquireLocksOnSubLinks(), AcquireRewriteLocks(), AddQual(), adjustJoinTreeList(), Assert, ChangeVarNodes(), checkExprHasSubLink(), CMD_INSERT, CMD_UPDATE, CMD_UTILITY, CombineRangeTables(), contain_vars_of_level(), copyObject, Query::cteList, CommonTableExpr::ctename, ereport, errcode(), errdetail(), errmsg, ERROR, fb(), acquireLocksOnSubLinks_context::for_execute, getInsertSelectQuery(), Query::jointree, lfirst, list_concat(), list_length(), NIL, OffsetVarNodes(), ONCONFLICT_SELECT, PRS2_NEW_VARNO, PRS2_OLD_VARNO, FromExpr::quals, rangeTableEntry_used(), REPLACEVARS_CHANGE_VARNO, REPLACEVARS_REPORT_ERROR, REPLACEVARS_SUBSTITUTE_NULL, ReplaceVarsFromTargetList(), Query::returningList, rt_fetch, Query::rtable, RTE_FUNCTION, RTE_RELATION, RTE_SUBQUERY, RTE_TABLEFUNC, RTE_VALUES, and Query::targetList.

Referenced by fireRules().

rewriteTargetListIU()

static List * rewriteTargetListIU ( List *  targetList, CmdType  commandType, OverridingKind  override, Relation  target_relation, RangeTblEntry *  values_rte, int  values_rte_index, Bitmapset **  unused_values_attrnos  )

static

Definition at line 790 of file rewriteHandler.c.

{
    TargetEntry **new_tles;
    List       *new_tlist = NIL;
    List       *junk_tlist = NIL;
    Form_pg_attribute att_tup;
    int         attrno,
                next_junk_attrno,
                numattrs;
    ListCell   *temp;
    Bitmapset  *default_only_cols = NULL;
 
    /*
     * We process the normal (non-junk) attributes by scanning the input tlist
     * once and transferring TLEs into an array, then scanning the array to
     * build an output tlist.  This avoids O(N^2) behavior for large numbers
     * of attributes.
     *
     * Junk attributes are tossed into a separate list during the same tlist
     * scan, then appended to the reconstructed tlist.
     */
    numattrs = RelationGetNumberOfAttributes(target_relation);
    new_tles = (TargetEntry **) palloc0(numattrs * sizeof(TargetEntry *));
    next_junk_attrno = numattrs + 1;
 
    foreach(temp, targetList)
    {
        TargetEntry *old_tle = (TargetEntry *) lfirst(temp);
 
        if (!old_tle->resjunk)
        {
            /* Normal attr: stash it into new_tles[] */
            attrno = old_tle->resno;
            if (attrno < 1 || attrno > numattrs)
                elog(ERROR, "bogus resno %d in targetlist", attrno);
            att_tup = TupleDescAttr(target_relation->rd_att, attrno - 1);
 
            /* We can (and must) ignore deleted attributes */
            if (att_tup->attisdropped)
                continue;
 
            /* Merge with any prior assignment to same attribute */
            new_tles[attrno - 1] =
                process_matched_tle(old_tle,
                                    new_tles[attrno - 1],
                                    NameStr(att_tup->attname));
        }
        else
        {
            /*
             * Copy all resjunk tlist entries to junk_tlist, and assign them
             * resnos above the last real resno.
             *
             * Typical junk entries include ORDER BY or GROUP BY expressions
             * (are these actually possible in an INSERT or UPDATE?), system
             * attribute references, etc.
             */
 
            /* Get the resno right, but don't copy unnecessarily */
            if (old_tle->resno != next_junk_attrno)
            {
                old_tle = flatCopyTargetEntry(old_tle);
                old_tle->resno = next_junk_attrno;
            }
            junk_tlist = lappend(junk_tlist, old_tle);
            next_junk_attrno++;
        }
    }
 
    for (attrno = 1; attrno <= numattrs; attrno++)
    {
        TargetEntry *new_tle = new_tles[attrno - 1];
        bool        apply_default;
 
        att_tup = TupleDescAttr(target_relation->rd_att, attrno - 1);
 
        /* We can (and must) ignore deleted attributes */
        if (att_tup->attisdropped)
            continue;
 
        /*
         * Handle the two cases where we need to insert a default expression:
         * it's an INSERT and there's no tlist entry for the column, or the
         * tlist entry is a DEFAULT placeholder node.
         */
        apply_default = ((new_tle == NULL && commandType == CMD_INSERT) ||
                         (new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)));
 
        if (commandType == CMD_INSERT)
        {
            int         values_attrno = 0;
 
            /* Source attribute number for values that come from a VALUES RTE */
            if (values_rte && new_tle && IsA(new_tle->expr, Var))
            {
                Var        *var = (Var *) new_tle->expr;
 
                if (var->varno == values_rte_index)
                    values_attrno = var->varattno;
            }
 
            /*
             * Can only insert DEFAULT into GENERATED ALWAYS identity columns,
             * unless either OVERRIDING USER VALUE or OVERRIDING SYSTEM VALUE
             * is specified.
             */
            if (att_tup->attidentity == ATTRIBUTE_IDENTITY_ALWAYS && !apply_default)
            {
                if (override == OVERRIDING_USER_VALUE)
                    apply_default = true;
                else if (override != OVERRIDING_SYSTEM_VALUE)
                {
                    /*
                     * If this column's values come from a VALUES RTE, test
                     * whether it contains only SetToDefault items.  Since the
                     * VALUES list might be quite large, we arrange to only
                     * scan it once.
                     */
                    if (values_attrno != 0)
                    {
                        if (default_only_cols == NULL)
                            default_only_cols = findDefaultOnlyColumns(values_rte);
 
                        if (bms_is_member(values_attrno, default_only_cols))
                            apply_default = true;
                    }
 
                    if (!apply_default)
                        ereport(ERROR,
                                (errcode(ERRCODE_GENERATED_ALWAYS),
                                 errmsg("cannot insert a non-DEFAULT value into column \"%s\"",
                                        NameStr(att_tup->attname)),
                                 errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
                                           NameStr(att_tup->attname)),
                                 errhint("Use OVERRIDING SYSTEM VALUE to override.")));
                }
            }
 
            /*
             * Although inserting into a GENERATED BY DEFAULT identity column
             * is allowed, apply the default if OVERRIDING USER VALUE is
             * specified.
             */
            if (att_tup->attidentity == ATTRIBUTE_IDENTITY_BY_DEFAULT &&
                override == OVERRIDING_USER_VALUE)
                apply_default = true;
 
            /*
             * Can only insert DEFAULT into generated columns.  (The
             * OVERRIDING clause does not apply to generated columns, so we
             * don't consider it here.)
             */
            if (att_tup->attgenerated && !apply_default)
            {
                /*
                 * If this column's values come from a VALUES RTE, test
                 * whether it contains only SetToDefault items, as above.
                 */
                if (values_attrno != 0)
                {
                    if (default_only_cols == NULL)
                        default_only_cols = findDefaultOnlyColumns(values_rte);
 
                    if (bms_is_member(values_attrno, default_only_cols))
                        apply_default = true;
                }
 
                if (!apply_default)
                    ereport(ERROR,
                            (errcode(ERRCODE_GENERATED_ALWAYS),
                             errmsg("cannot insert a non-DEFAULT value into column \"%s\"",
                                    NameStr(att_tup->attname)),
                             errdetail("Column \"%s\" is a generated column.",
                                       NameStr(att_tup->attname))));
            }
 
            /*
             * For an INSERT from a VALUES RTE, return the attribute numbers
             * of any VALUES columns that will no longer be used (due to the
             * targetlist entry being replaced by a default expression).
             */
            if (values_attrno != 0 && apply_default && unused_values_attrnos)
                *unused_values_attrnos = bms_add_member(*unused_values_attrnos,
                                                        values_attrno);
        }
 
        /*
         * Updates to identity and generated columns follow the same rules as
         * above, except that UPDATE doesn't admit OVERRIDING clauses.  Also,
         * the source can't be a VALUES RTE, so we needn't consider that.
         */
        if (commandType == CMD_UPDATE)
        {
            if (att_tup->attidentity == ATTRIBUTE_IDENTITY_ALWAYS &&
                new_tle && !apply_default)
                ereport(ERROR,
                        (errcode(ERRCODE_GENERATED_ALWAYS),
                         errmsg("column \"%s\" can only be updated to DEFAULT",
                                NameStr(att_tup->attname)),
                         errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
                                   NameStr(att_tup->attname))));
 
            if (att_tup->attgenerated && new_tle && !apply_default)
                ereport(ERROR,
                        (errcode(ERRCODE_GENERATED_ALWAYS),
                         errmsg("column \"%s\" can only be updated to DEFAULT",
                                NameStr(att_tup->attname)),
                         errdetail("Column \"%s\" is a generated column.",
                                   NameStr(att_tup->attname))));
        }
 
        if (att_tup->attgenerated)
        {
            /*
             * virtual generated column stores a null value; stored generated
             * column will be fixed in executor
             */
            new_tle = NULL;
        }
        else if (apply_default)
        {
            Node       *new_expr;
 
            new_expr = build_column_default(target_relation, attrno);
 
            /*
             * If there is no default (ie, default is effectively NULL), we
             * can omit the tlist entry in the INSERT case, since the planner
             * can insert a NULL for itself, and there's no point in spending
             * any more rewriter cycles on the entry.  But in the UPDATE case
             * we've got to explicitly set the column to NULL.
             */
            if (!new_expr)
            {
                if (commandType == CMD_INSERT)
                    new_tle = NULL;
                else
                    new_expr = coerce_null_to_domain(att_tup->atttypid,
                                                     att_tup->atttypmod,
                                                     att_tup->attcollation,
                                                     att_tup->attlen,
                                                     att_tup->attbyval);
            }
 
            if (new_expr)
                new_tle = makeTargetEntry((Expr *) new_expr,
                                          attrno,
                                          pstrdup(NameStr(att_tup->attname)),
                                          false);
        }
 
        if (new_tle)
            new_tlist = lappend(new_tlist, new_tle);
    }
 
    pfree(new_tles);
 
    return list_concat(new_tlist, junk_tlist);
}

References bms_add_member(), bms_is_member(), build_column_default(), CMD_INSERT, CMD_UPDATE, coerce_null_to_domain(), elog, ereport, errcode(), errdetail(), errhint(), errmsg, ERROR, fb(), findDefaultOnlyColumns(), flatCopyTargetEntry(), IsA, lappend(), lfirst, list_concat(), makeTargetEntry(), NameStr, NIL, OVERRIDING_SYSTEM_VALUE, OVERRIDING_USER_VALUE, palloc0(), pfree(), process_matched_tle(), pstrdup(), RelationGetNumberOfAttributes, TargetEntry::resno, TupleDescAttr(), Var::varattno, and Var::varno.

Referenced by RewriteQuery().

rewriteTargetView()

static Query * rewriteTargetView ( Query *  parsetree, Relation  view  )

static

Definition at line 3242 of file rewriteHandler.c.

{
    Query      *viewquery;
    bool        insert_or_update;
    const char *auto_update_detail;
    RangeTblRef *rtr;
    int         base_rt_index;
    int         new_rt_index;
    RangeTblEntry *base_rte;
    RangeTblEntry *view_rte;
    RangeTblEntry *new_rte;
    RTEPermissionInfo *base_perminfo;
    RTEPermissionInfo *view_perminfo;
    RTEPermissionInfo *new_perminfo;
    Relation    base_rel;
    List       *view_targetlist;
    ListCell   *lc;
 
    /*
     * Get the Query from the view's ON SELECT rule.  We're going to munge the
     * Query to change the view's base relation into the target relation,
     * along with various other changes along the way, so we need to make a
     * copy of it (get_view_query() returns a pointer into the relcache, so we
     * have to treat it as read-only).
     */
    viewquery = copyObject(get_view_query(view));
 
    /* Locate RTE and perminfo describing the view in the outer query */
    view_rte = rt_fetch(parsetree->resultRelation, parsetree->rtable);
    view_perminfo = getRTEPermissionInfo(parsetree->rteperminfos, view_rte);
 
    /*
     * Are we doing INSERT/UPDATE, or MERGE containing INSERT/UPDATE?  If so,
     * various additional checks on the view columns need to be applied, and
     * any view CHECK OPTIONs need to be enforced.
     */
    insert_or_update =
        (parsetree->commandType == CMD_INSERT ||
         parsetree->commandType == CMD_UPDATE);
 
    if (parsetree->commandType == CMD_MERGE)
    {
        foreach_node(MergeAction, action, parsetree->mergeActionList)
        {
            if (action->commandType == CMD_INSERT ||
                action->commandType == CMD_UPDATE)
            {
                insert_or_update = true;
                break;
            }
        }
    }
 
    /* Check if the expansion of non-system views are restricted */
    if (unlikely((restrict_nonsystem_relation_kind & RESTRICT_RELKIND_VIEW) != 0 &&
                 RelationGetRelid(view) >= FirstNormalObjectId))
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("access to non-system view \"%s\" is restricted",
                        RelationGetRelationName(view))));
 
    /*
     * The view must be updatable, else fail.
     *
     * If we are doing INSERT/UPDATE (or MERGE containing INSERT/UPDATE), we
     * also check that there is at least one updatable column.
     */
    auto_update_detail =
        view_query_is_auto_updatable(viewquery, insert_or_update);
 
    if (auto_update_detail)
        error_view_not_updatable(view,
                                 parsetree->commandType,
                                 parsetree->mergeActionList,
                                 auto_update_detail);
 
    /*
     * For INSERT/UPDATE (or MERGE containing INSERT/UPDATE) the modified
     * columns must all be updatable.
     */
    if (insert_or_update)
    {
        Bitmapset  *modified_cols;
        char       *non_updatable_col;
 
        /*
         * Compute the set of modified columns as those listed in the result
         * RTE's insertedCols and/or updatedCols sets plus those that are
         * targets of the query's targetlist(s).  We must consider the query's
         * targetlist because rewriteTargetListIU may have added additional
         * targetlist entries for view defaults, and these must also be
         * updatable.  But rewriteTargetListIU can also remove entries if they
         * are DEFAULT markers and the column's default is NULL, so
         * considering only the targetlist would also be wrong.
         */
        modified_cols = bms_union(view_perminfo->insertedCols,
                                  view_perminfo->updatedCols);
 
        foreach(lc, parsetree->targetList)
        {
            TargetEntry *tle = (TargetEntry *) lfirst(lc);
 
            if (!tle->resjunk)
                modified_cols = bms_add_member(modified_cols,
                                               tle->resno - FirstLowInvalidHeapAttributeNumber);
        }
 
        if (parsetree->onConflict)
        {
            foreach(lc, parsetree->onConflict->onConflictSet)
            {
                TargetEntry *tle = (TargetEntry *) lfirst(lc);
 
                if (!tle->resjunk)
                    modified_cols = bms_add_member(modified_cols,
                                                   tle->resno - FirstLowInvalidHeapAttributeNumber);
            }
        }
 
        foreach_node(MergeAction, action, parsetree->mergeActionList)
        {
            if (action->commandType == CMD_INSERT ||
                action->commandType == CMD_UPDATE)
            {
                foreach_node(TargetEntry, tle, action->targetList)
                {
                    if (!tle->resjunk)
                        modified_cols = bms_add_member(modified_cols,
                                                       tle->resno - FirstLowInvalidHeapAttributeNumber);
                }
            }
        }
 
        auto_update_detail = view_cols_are_auto_updatable(viewquery,
                                                          modified_cols,
                                                          NULL,
                                                          &non_updatable_col);
        if (auto_update_detail)
        {
            /*
             * This is a different error, caused by an attempt to update a
             * non-updatable column in an otherwise updatable view.
             */
            switch (parsetree->commandType)
            {
                case CMD_INSERT:
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot insert into column \"%s\" of view \"%s\"",
                                    non_updatable_col,
                                    RelationGetRelationName(view)),
                             errdetail_internal("%s", _(auto_update_detail))));
                    break;
                case CMD_UPDATE:
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot update column \"%s\" of view \"%s\"",
                                    non_updatable_col,
                                    RelationGetRelationName(view)),
                             errdetail_internal("%s", _(auto_update_detail))));
                    break;
                case CMD_MERGE:
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot merge into column \"%s\" of view \"%s\"",
                                    non_updatable_col,
                                    RelationGetRelationName(view)),
                             errdetail_internal("%s", _(auto_update_detail))));
                    break;
                default:
                    elog(ERROR, "unrecognized CmdType: %d",
                         (int) parsetree->commandType);
                    break;
            }
        }
    }
 
    /*
     * For MERGE, there must not be any INSTEAD OF triggers on an otherwise
     * updatable view.  The caller already checked that there isn't a full set
     * of INSTEAD OF triggers, so this is to guard against having a partial
     * set (mixing auto-update and trigger-update actions in a single command
     * isn't supported).
     */
    if (parsetree->commandType == CMD_MERGE)
    {
        foreach_node(MergeAction, action, parsetree->mergeActionList)
        {
            if (action->commandType != CMD_NOTHING &&
                view_has_instead_trigger(view, action->commandType, NIL))
                ereport(ERROR,
                        errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                        errmsg("cannot merge into view \"%s\"",
                               RelationGetRelationName(view)),
                        errdetail("MERGE is not supported for views with INSTEAD OF triggers for some actions but not all."),
                        errhint("To enable merging into the view, either provide a full set of INSTEAD OF triggers or drop the existing INSTEAD OF triggers."));
        }
    }
 
    /*
     * If we get here, view_query_is_auto_updatable() has verified that the
     * view contains a single base relation.
     */
    Assert(list_length(viewquery->jointree->fromlist) == 1);
    rtr = linitial_node(RangeTblRef, viewquery->jointree->fromlist);
 
    base_rt_index = rtr->rtindex;
    base_rte = rt_fetch(base_rt_index, viewquery->rtable);
    Assert(base_rte->rtekind == RTE_RELATION);
    base_perminfo = getRTEPermissionInfo(viewquery->rteperminfos, base_rte);
 
    /*
     * Up to now, the base relation hasn't been touched at all in our query.
     * We need to acquire lock on it before we try to do anything with it.
     * (The subsequent recursive call of RewriteQuery will suppose that we
     * already have the right lock!)  Since it will become the query target
     * relation, RowExclusiveLock is always the right thing.
     */
    base_rel = relation_open(base_rte->relid, RowExclusiveLock);
 
    /*
     * While we have the relation open, update the RTE's relkind, just in case
     * it changed since this view was made (cf. AcquireRewriteLocks).
     */
    base_rte->relkind = base_rel->rd_rel->relkind;
 
    /*
     * If the view query contains any sublink subqueries then we need to also
     * acquire locks on any relations they refer to.  We know that there won't
     * be any subqueries in the range table or CTEs, so we can skip those, as
     * in AcquireRewriteLocks.
     */
    if (viewquery->hasSubLinks)
    {
        acquireLocksOnSubLinks_context context;
 
        context.for_execute = true;
        query_tree_walker(viewquery, acquireLocksOnSubLinks, &context,
                          QTW_IGNORE_RC_SUBQUERIES);
    }
 
    /*
     * Create a new target RTE describing the base relation, and add it to the
     * outer query's rangetable.  (What's happening in the next few steps is
     * very much like what the planner would do to "pull up" the view into the
     * outer query.  Perhaps someday we should refactor things enough so that
     * we can share code with the planner.)
     *
     * Be sure to set rellockmode to the correct thing for the target table.
     * Since we copied the whole viewquery above, we can just scribble on
     * base_rte instead of copying it.
     */
    new_rte = base_rte;
    new_rte->rellockmode = RowExclusiveLock;
 
    parsetree->rtable = lappend(parsetree->rtable, new_rte);
    new_rt_index = list_length(parsetree->rtable);
 
    /*
     * INSERTs never inherit.  For UPDATE/DELETE/MERGE, we use the view
     * query's inheritance flag for the base relation.
     */
    if (parsetree->commandType == CMD_INSERT)
        new_rte->inh = false;
 
    /*
     * Adjust the view's targetlist Vars to reference the new target RTE, ie
     * make their varnos be new_rt_index instead of base_rt_index.  There can
     * be no Vars for other rels in the tlist, so this is sufficient to pull
     * up the tlist expressions for use in the outer query.  The tlist will
     * provide the replacement expressions used by ReplaceVarsFromTargetList
     * below.
     */
    view_targetlist = viewquery->targetList;
 
    ChangeVarNodes((Node *) view_targetlist,
                   base_rt_index,
                   new_rt_index,
                   0);
 
    /*
     * If the view has "security_invoker" set, mark the new target relation
     * for the permissions checks that we want to enforce against the query
     * caller. Otherwise we want to enforce them against the view owner.
     *
     * At the relation level, require the same INSERT/UPDATE/DELETE
     * permissions that the query caller needs against the view.  We drop the
     * ACL_SELECT bit that is presumably in new_perminfo->requiredPerms
     * initially.
     *
     * Note: the original view's RTEPermissionInfo remains in the query's
     * rteperminfos so that the executor still performs appropriate
     * permissions checks for the query caller's use of the view.
     *
     * Disregard the perminfo in viewquery->rteperminfos that the base_rte
     * would currently be pointing at, because we'd like it to point now to a
     * new one that will be filled below.  Must set perminfoindex to 0 to not
     * trip over the Assert in addRTEPermissionInfo().
     */
    new_rte->perminfoindex = 0;
    new_perminfo = addRTEPermissionInfo(&parsetree->rteperminfos, new_rte);
    if (RelationHasSecurityInvoker(view))
        new_perminfo->checkAsUser = InvalidOid;
    else
        new_perminfo->checkAsUser = view->rd_rel->relowner;
    new_perminfo->requiredPerms = view_perminfo->requiredPerms;
 
    /*
     * Now for the per-column permissions bits.
     *
     * Initially, new_perminfo (base_perminfo) contains selectedCols
     * permission check bits for all base-rel columns referenced by the view,
     * but since the view is a SELECT query its insertedCols/updatedCols is
     * empty.  We set insertedCols and updatedCols to include all the columns
     * the outer query is trying to modify, adjusting the column numbers as
     * needed.  But we leave selectedCols as-is, so the view owner must have
     * read permission for all columns used in the view definition, even if
     * some of them are not read by the outer query.  We could try to limit
     * selectedCols to only columns used in the transformed query, but that
     * does not correspond to what happens in ordinary SELECT usage of a view:
     * all referenced columns must have read permission, even if optimization
     * finds that some of them can be discarded during query transformation.
     * The flattening we're doing here is an optional optimization, too.  (If
     * you are unpersuaded and want to change this, note that applying
     * adjust_view_column_set to view_perminfo->selectedCols is clearly *not*
     * the right answer, since that neglects base-rel columns used in the
     * view's WHERE quals.)
     *
     * This step needs the modified view targetlist, so we have to do things
     * in this order.
     */
    Assert(bms_is_empty(new_perminfo->insertedCols) &&
           bms_is_empty(new_perminfo->updatedCols));
 
    new_perminfo->selectedCols = base_perminfo->selectedCols;
 
    new_perminfo->insertedCols =
        adjust_view_column_set(view_perminfo->insertedCols, view_targetlist);
 
    new_perminfo->updatedCols =
        adjust_view_column_set(view_perminfo->updatedCols, view_targetlist);
 
    /*
     * Move any security barrier quals from the view RTE onto the new target
     * RTE.  Any such quals should now apply to the new target RTE and will
     * not reference the original view RTE in the rewritten query.
     */
    new_rte->securityQuals = view_rte->securityQuals;
    view_rte->securityQuals = NIL;
 
    /*
     * Now update all Vars in the outer query that reference the view to
     * reference the appropriate column of the base relation instead.
     */
    parsetree = (Query *)
        ReplaceVarsFromTargetList((Node *) parsetree,
                                  parsetree->resultRelation,
                                  0,
                                  view_rte,
                                  view_targetlist,
                                  new_rt_index,
                                  REPLACEVARS_REPORT_ERROR,
                                  0,
                                  NULL);
 
    /*
     * Update all other RTI references in the query that point to the view
     * (for example, parsetree->resultRelation itself) to point to the new
     * base relation instead.  Vars will not be affected since none of them
     * reference parsetree->resultRelation any longer.
     */
    ChangeVarNodes((Node *) parsetree,
                   parsetree->resultRelation,
                   new_rt_index,
                   0);
    Assert(parsetree->resultRelation == new_rt_index);
 
    /*
     * For INSERT/UPDATE we must also update resnos in the targetlist to refer
     * to columns of the base relation, since those indicate the target
     * columns to be affected.  Similarly, for MERGE we must update the resnos
     * in the merge action targetlists of any INSERT/UPDATE actions.
     *
     * Note that this destroys the resno ordering of the targetlists, but that
     * will be fixed when we recurse through RewriteQuery, which will invoke
     * rewriteTargetListIU again on the updated targetlists.
     */
    if (parsetree->commandType != CMD_DELETE)
    {
        foreach(lc, parsetree->targetList)
        {
            TargetEntry *tle = (TargetEntry *) lfirst(lc);
            TargetEntry *view_tle;
 
            if (tle->resjunk)
                continue;
 
            view_tle = get_tle_by_resno(view_targetlist, tle->resno);
            if (view_tle != NULL && !view_tle->resjunk && IsA(view_tle->expr, Var))
                tle->resno = ((Var *) view_tle->expr)->varattno;
            else
                elog(ERROR, "attribute number %d not found in view targetlist",
                     tle->resno);
        }
 
        foreach_node(MergeAction, action, parsetree->mergeActionList)
        {
            if (action->commandType == CMD_INSERT ||
                action->commandType == CMD_UPDATE)
            {
                foreach_node(TargetEntry, tle, action->targetList)
                {
                    TargetEntry *view_tle;
 
                    if (tle->resjunk)
                        continue;
 
                    view_tle = get_tle_by_resno(view_targetlist, tle->resno);
                    if (view_tle != NULL && !view_tle->resjunk && IsA(view_tle->expr, Var))
                        tle->resno = ((Var *) view_tle->expr)->varattno;
                    else
                        elog(ERROR, "attribute number %d not found in view targetlist",
                             tle->resno);
                }
            }
        }
    }
 
    /*
     * For INSERT .. ON CONFLICT .. DO SELECT/UPDATE, we must also update
     * assorted stuff in the onConflict data structure.
     */
    if (parsetree->onConflict &&
        (parsetree->onConflict->action == ONCONFLICT_UPDATE ||
         parsetree->onConflict->action == ONCONFLICT_SELECT))
    {
        Index       old_exclRelIndex,
                    new_exclRelIndex;
        ParseNamespaceItem *new_exclNSItem;
        RangeTblEntry *new_exclRte;
        List       *tmp_tlist;
 
        /*
         * For ON CONFLICT DO UPDATE, update the resnos in the auxiliary
         * UPDATE targetlist to refer to columns of the base relation.
         */
        foreach(lc, parsetree->onConflict->onConflictSet)
        {
            TargetEntry *tle = (TargetEntry *) lfirst(lc);
            TargetEntry *view_tle;
 
            if (tle->resjunk)
                continue;
 
            view_tle = get_tle_by_resno(view_targetlist, tle->resno);
            if (view_tle != NULL && !view_tle->resjunk && IsA(view_tle->expr, Var))
                tle->resno = ((Var *) view_tle->expr)->varattno;
            else
                elog(ERROR, "attribute number %d not found in view targetlist",
                     tle->resno);
        }
 
        /*
         * Create a new RTE for the EXCLUDED pseudo-relation, using the
         * query's new base rel (which may well have a different column list
         * from the view, hence we need a new column alias list).  This should
         * match transformOnConflictClause.  In particular, note that the
         * relkind is set to composite to signal that we're not dealing with
         * an actual relation.
         */
        old_exclRelIndex = parsetree->onConflict->exclRelIndex;
 
        new_exclNSItem = addRangeTableEntryForRelation(make_parsestate(NULL),
                                                       base_rel,
                                                       RowExclusiveLock,
                                                       makeAlias("excluded", NIL),
                                                       false, false);
        new_exclRte = new_exclNSItem->p_rte;
        new_exclRte->relkind = RELKIND_COMPOSITE_TYPE;
        /* Ignore the RTEPermissionInfo that would've been added. */
        new_exclRte->perminfoindex = 0;
 
        parsetree->rtable = lappend(parsetree->rtable, new_exclRte);
        new_exclRelIndex = parsetree->onConflict->exclRelIndex =
            list_length(parsetree->rtable);
 
        /*
         * Replace the targetlist for the EXCLUDED pseudo-relation with a new
         * one, representing the columns from the new base relation.
         */
        parsetree->onConflict->exclRelTlist =
            BuildOnConflictExcludedTargetlist(base_rel, new_exclRelIndex);
 
        /*
         * Update all Vars in the ON CONFLICT clause that refer to the old
         * EXCLUDED pseudo-relation.  We want to use the column mappings
         * defined in the view targetlist, but we need the outputs to refer to
         * the new EXCLUDED pseudo-relation rather than the new target RTE.
         * Also notice that "EXCLUDED.*" will be expanded using the view's
         * rowtype, which seems correct.
         */
        tmp_tlist = copyObject(view_targetlist);
 
        ChangeVarNodes((Node *) tmp_tlist, new_rt_index,
                       new_exclRelIndex, 0);
 
        parsetree->onConflict = (OnConflictExpr *)
            ReplaceVarsFromTargetList((Node *) parsetree->onConflict,
                                      old_exclRelIndex,
                                      0,
                                      view_rte,
                                      tmp_tlist,
                                      new_rt_index,
                                      REPLACEVARS_REPORT_ERROR,
                                      0,
                                      &parsetree->hasSubLinks);
    }
 
    if (parsetree->forPortionOf && parsetree->commandType == CMD_UPDATE)
    {
        /*
         * Like the INSERT/UPDATE code above, update the resnos in the
         * auxiliary UPDATE targetlist to refer to columns of the base
         * relation.
         */
        foreach(lc, parsetree->forPortionOf->rangeTargetList)
        {
            TargetEntry *tle = (TargetEntry *) lfirst(lc);
            TargetEntry *view_tle;
 
            if (tle->resjunk)
                continue;
 
            view_tle = get_tle_by_resno(view_targetlist, tle->resno);
            if (view_tle != NULL && !view_tle->resjunk && IsA(view_tle->expr, Var))
                tle->resno = ((Var *) view_tle->expr)->varattno;
            else
                elog(ERROR, "attribute number %d not found in view targetlist",
                     tle->resno);
        }
    }
 
    /*
     * For UPDATE/DELETE/MERGE, pull up any WHERE quals from the view.  We
     * know that any Vars in the quals must reference the one base relation,
     * so we need only adjust their varnos to reference the new target (just
     * the same as we did with the view targetlist).
     *
     * If it's a security-barrier view, its WHERE quals must be applied before
     * quals from the outer query, so we attach them to the RTE as security
     * barrier quals rather than adding them to the main WHERE clause.
     *
     * For INSERT, the view's quals can be ignored in the main query.
     */
    if (parsetree->commandType != CMD_INSERT &&
        viewquery->jointree->quals != NULL)
    {
        Node       *viewqual = (Node *) viewquery->jointree->quals;
 
        /*
         * Even though we copied viewquery already at the top of this
         * function, we must duplicate the viewqual again here, because we may
         * need to use the quals again below for a WithCheckOption clause.
         */
        viewqual = copyObject(viewqual);
 
        ChangeVarNodes(viewqual, base_rt_index, new_rt_index, 0);
 
        if (RelationIsSecurityView(view))
        {
            /*
             * The view's quals go in front of existing barrier quals: those
             * would have come from an outer level of security-barrier view,
             * and so must get evaluated later.
             *
             * Note: the parsetree has been mutated, so the new_rte pointer is
             * stale and needs to be re-computed.
             */
            new_rte = rt_fetch(new_rt_index, parsetree->rtable);
            new_rte->securityQuals = lcons(viewqual, new_rte->securityQuals);
 
            /*
             * Do not set parsetree->hasRowSecurity, because these aren't RLS
             * conditions (they aren't affected by enabling/disabling RLS).
             */
 
            /*
             * Make sure that the query is marked correctly if the added qual
             * has sublinks.
             */
            if (!parsetree->hasSubLinks)
                parsetree->hasSubLinks = checkExprHasSubLink(viewqual);
        }
        else
            AddQual(parsetree, viewqual);
    }
 
    /*
     * For INSERT/UPDATE (or MERGE containing INSERT/UPDATE), if the view has
     * the WITH CHECK OPTION, or any parent view specified WITH CASCADED CHECK
     * OPTION, add the quals from the view to the query's withCheckOptions
     * list.
     */
    if (insert_or_update)
    {
        bool        has_wco = RelationHasCheckOption(view);
        bool        cascaded = RelationHasCascadedCheckOption(view);
 
        /*
         * If the parent view has a cascaded check option, treat this view as
         * if it also had a cascaded check option.
         *
         * New WithCheckOptions are added to the start of the list, so if
         * there is a cascaded check option, it will be the first item in the
         * list.
         */
        if (parsetree->withCheckOptions != NIL)
        {
            WithCheckOption *parent_wco =
                (WithCheckOption *) linitial(parsetree->withCheckOptions);
 
            if (parent_wco->cascaded)
            {
                has_wco = true;
                cascaded = true;
            }
        }
 
        /*
         * Add the new WithCheckOption to the start of the list, so that
         * checks on inner views are run before checks on outer views, as
         * required by the SQL standard.
         *
         * If the new check is CASCADED, we need to add it even if this view
         * has no quals, since there may be quals on child views.  A LOCAL
         * check can be omitted if this view has no quals.
         */
        if (has_wco && (cascaded || viewquery->jointree->quals != NULL))
        {
            WithCheckOption *wco;
 
            wco = makeNode(WithCheckOption);
            wco->kind = WCO_VIEW_CHECK;
            wco->relname = pstrdup(RelationGetRelationName(view));
            wco->polname = NULL;
            wco->qual = NULL;
            wco->cascaded = cascaded;
 
            parsetree->withCheckOptions = lcons(wco,
                                                parsetree->withCheckOptions);
 
            if (viewquery->jointree->quals != NULL)
            {
                wco->qual = (Node *) viewquery->jointree->quals;
                ChangeVarNodes(wco->qual, base_rt_index, new_rt_index, 0);
 
                /*
                 * For INSERT, make sure that the query is marked correctly if
                 * the added qual has sublinks.  This can be skipped for
                 * UPDATE/MERGE, since the same qual will have already been
                 * added above, and the check will already have been done.
                 */
                if (!parsetree->hasSubLinks &&
                    parsetree->commandType == CMD_INSERT)
                    parsetree->hasSubLinks = checkExprHasSubLink(wco->qual);
            }
        }
    }
 
    table_close(base_rel, NoLock);
 
    return parsetree;
}

References _, acquireLocksOnSubLinks(), OnConflictExpr::action, AddQual(), addRangeTableEntryForRelation(), addRTEPermissionInfo(), adjust_view_column_set(), Assert, bms_add_member(), bms_is_empty, bms_union(), BuildOnConflictExcludedTargetlist(), ChangeVarNodes(), checkExprHasSubLink(), CMD_DELETE, CMD_INSERT, CMD_MERGE, CMD_NOTHING, CMD_UPDATE, Query::commandType, copyObject, elog, ereport, errcode(), errdetail(), errdetail_internal(), errhint(), errmsg, ERROR, error_view_not_updatable(), OnConflictExpr::exclRelIndex, OnConflictExpr::exclRelTlist, fb(), FirstLowInvalidHeapAttributeNumber, FirstNormalObjectId, acquireLocksOnSubLinks_context::for_execute, foreach_node, Query::forPortionOf, get_tle_by_resno(), get_view_query(), getRTEPermissionInfo(), InvalidOid, IsA, lappend(), lcons(), lfirst, linitial, linitial_node, list_length(), make_parsestate(), makeAlias(), makeNode, Query::mergeActionList, NIL, NoLock, Query::onConflict, ONCONFLICT_SELECT, ONCONFLICT_UPDATE, OnConflictExpr::onConflictSet, pstrdup(), QTW_IGNORE_RC_SUBQUERIES, query_tree_walker, ForPortionOfExpr::rangeTargetList, RelationData::rd_rel, relation_open(), RelationGetRelationName, RelationGetRelid, RelationHasCascadedCheckOption, RelationHasCheckOption, RelationHasSecurityInvoker, RelationIsSecurityView, REPLACEVARS_REPORT_ERROR, ReplaceVarsFromTargetList(), restrict_nonsystem_relation_kind, RESTRICT_RELKIND_VIEW, RowExclusiveLock, rt_fetch, Query::rtable, RTE_RELATION, table_close(), Query::targetList, unlikely, view_cols_are_auto_updatable(), view_has_instead_trigger(), view_query_is_auto_updatable(), and WCO_VIEW_CHECK.

Referenced by RewriteQuery().

rewriteValuesRTE()

static bool rewriteValuesRTE ( Query *  parsetree, RangeTblEntry *  rte, int  rti, Relation  target_relation, Bitmapset *  unused_cols  )

static

Definition at line 1431 of file rewriteHandler.c.

{
    List       *newValues;
    ListCell   *lc;
    bool        isAutoUpdatableView;
    bool        allReplaced;
    int         numattrs;
    int        *attrnos;
 
    /* Steps below are not sensible for non-INSERT queries */
    Assert(parsetree->commandType == CMD_INSERT);
    Assert(rte->rtekind == RTE_VALUES);
 
    /*
     * Rebuilding all the lists is a pretty expensive proposition in a big
     * VALUES list, and it's a waste of time if there aren't any DEFAULT
     * placeholders.  So first scan to see if there are any.
     */
    if (!searchForDefault(rte))
        return true;            /* nothing to do */
 
    /*
     * Scan the targetlist for entries referring to the VALUES RTE, and note
     * the target attributes. As noted above, we should only need to do this
     * for targetlist entries containing simple Vars --- nothing else in the
     * VALUES RTE should contain DEFAULT items (except possibly for unused
     * columns), and we complain if such a thing does occur.
     */
    numattrs = list_length(linitial(rte->values_lists));
    attrnos = (int *) palloc0(numattrs * sizeof(int));
 
    foreach(lc, parsetree->targetList)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(lc);
 
        if (IsA(tle->expr, Var))
        {
            Var        *var = (Var *) tle->expr;
 
            if (var->varno == rti)
            {
                int         attrno = var->varattno;
 
                Assert(attrno >= 1 && attrno <= numattrs);
                attrnos[attrno - 1] = tle->resno;
            }
        }
    }
 
    /*
     * Check if the target relation is an auto-updatable view, in which case
     * unresolved defaults will be left untouched rather than being set to
     * NULL.
     */
    isAutoUpdatableView = false;
    if (target_relation->rd_rel->relkind == RELKIND_VIEW &&
        !view_has_instead_trigger(target_relation, CMD_INSERT, NIL))
    {
        List       *locks;
        bool        hasUpdate;
        bool        found;
        ListCell   *l;
 
        /* Look for an unconditional DO INSTEAD rule */
        locks = matchLocks(CMD_INSERT, target_relation,
                           parsetree->resultRelation, parsetree, &hasUpdate);
 
        found = false;
        foreach(l, locks)
        {
            RewriteRule *rule_lock = (RewriteRule *) lfirst(l);
 
            if (rule_lock->isInstead &&
                rule_lock->qual == NULL)
            {
                found = true;
                break;
            }
        }
 
        /*
         * If we didn't find an unconditional DO INSTEAD rule, assume that the
         * view is auto-updatable.  If it isn't, rewriteTargetView() will
         * throw an error.
         */
        if (!found)
            isAutoUpdatableView = true;
    }
 
    newValues = NIL;
    allReplaced = true;
    foreach(lc, rte->values_lists)
    {
        List       *sublist = (List *) lfirst(lc);
        List       *newList = NIL;
        ListCell   *lc2;
        int         i;
 
        Assert(list_length(sublist) == numattrs);
 
        i = 0;
        foreach(lc2, sublist)
        {
            Node       *col = (Node *) lfirst(lc2);
            int         attrno = attrnos[i++];
 
            if (IsA(col, SetToDefault))
            {
                Form_pg_attribute att_tup;
                Node       *new_expr;
 
                /*
                 * If this column isn't used, just replace the DEFAULT with
                 * NULL (attrno will be 0 in this case because the targetlist
                 * entry will have been replaced by the default expression).
                 */
                if (bms_is_member(i, unused_cols))
                {
                    SetToDefault *def = (SetToDefault *) col;
 
                    newList = lappend(newList,
                                      makeNullConst(def->typeId,
                                                    def->typeMod,
                                                    def->collation));
                    continue;
                }
 
                if (attrno == 0)
                    elog(ERROR, "cannot set value in column %d to DEFAULT", i);
                Assert(attrno > 0 && attrno <= target_relation->rd_att->natts);
                att_tup = TupleDescAttr(target_relation->rd_att, attrno - 1);
 
                if (!att_tup->attisdropped)
                    new_expr = build_column_default(target_relation, attrno);
                else
                    new_expr = NULL;    /* force a NULL if dropped */
 
                /*
                 * If there is no default (ie, default is effectively NULL),
                 * we've got to explicitly set the column to NULL, unless the
                 * target relation is an auto-updatable view.
                 */
                if (!new_expr)
                {
                    if (isAutoUpdatableView)
                    {
                        /* Leave the value untouched */
                        newList = lappend(newList, col);
                        allReplaced = false;
                        continue;
                    }
 
                    new_expr = coerce_null_to_domain(att_tup->atttypid,
                                                     att_tup->atttypmod,
                                                     att_tup->attcollation,
                                                     att_tup->attlen,
                                                     att_tup->attbyval);
                }
                newList = lappend(newList, new_expr);
            }
            else
                newList = lappend(newList, col);
        }
        newValues = lappend(newValues, newList);
    }
    rte->values_lists = newValues;
 
    pfree(attrnos);
 
    return allReplaced;
}

References Assert, bms_is_member(), build_column_default(), CMD_INSERT, coerce_null_to_domain(), Query::commandType, elog, ERROR, fb(), i, IsA, lappend(), lfirst, linitial, list_length(), makeNullConst(), matchLocks(), NIL, palloc0(), pfree(), RTE_VALUES, searchForDefault(), Query::targetList, TupleDescAttr(), SetToDefault::typeId, Var::varattno, Var::varno, and view_has_instead_trigger().

Referenced by RewriteQuery().

rewriteValuesRTEToNulls()

static void rewriteValuesRTEToNulls ( Query *  parsetree, RangeTblEntry *  rte  )

static

Definition at line 1616 of file rewriteHandler.c.

{
    List       *newValues;
    ListCell   *lc;
 
    newValues = NIL;
    foreach(lc, rte->values_lists)
    {
        List       *sublist = (List *) lfirst(lc);
        List       *newList = NIL;
        ListCell   *lc2;
 
        foreach(lc2, sublist)
        {
            Node       *col = (Node *) lfirst(lc2);
 
            if (IsA(col, SetToDefault))
            {
                SetToDefault *def = (SetToDefault *) col;
 
                newList = lappend(newList, makeNullConst(def->typeId,
                                                         def->typeMod,
                                                         def->collation));
            }
            else
                newList = lappend(newList, col);
        }
        newValues = lappend(newValues, newList);
    }
    rte->values_lists = newValues;
}

References fb(), IsA, lappend(), lfirst, makeNullConst(), NIL, and SetToDefault::typeId.

Referenced by RewriteQuery().

searchForDefault()

static bool searchForDefault ( RangeTblEntry *  rte )

static

Definition at line 1317 of file rewriteHandler.c.

{
    ListCell   *lc;
 
    foreach(lc, rte->values_lists)
    {
        List       *sublist = (List *) lfirst(lc);
        ListCell   *lc2;
 
        foreach(lc2, sublist)
        {
            Node       *col = (Node *) lfirst(lc2);
 
            if (IsA(col, SetToDefault))
                return true;
        }
    }
    return false;
}

References fb(), IsA, and lfirst.

Referenced by rewriteValuesRTE().

view_col_is_auto_updatable()

static const char * view_col_is_auto_updatable ( RangeTblRef *  rtr, TargetEntry *  tle  )

static

Definition at line 2613 of file rewriteHandler.c.

{
    Var        *var = (Var *) tle->expr;
 
    /*
     * For now, the only updatable columns we support are those that are Vars
     * referring to user columns of the underlying base relation.
     *
     * The view targetlist may contain resjunk columns (e.g., a view defined
     * like "SELECT * FROM t ORDER BY a+b" is auto-updatable) but such columns
     * are not auto-updatable, and in fact should never appear in the outer
     * query's targetlist.
     */
    if (tle->resjunk)
        return gettext_noop("Junk view columns are not updatable.");
 
    if (!IsA(var, Var) ||
        var->varno != rtr->rtindex ||
        var->varlevelsup != 0)
        return gettext_noop("View columns that are not columns of their base relation are not updatable.");
 
    if (var->varattno < 0)
        return gettext_noop("View columns that refer to system columns are not updatable.");
 
    if (var->varattno == 0)
        return gettext_noop("View columns that return whole-row references are not updatable.");
 
    return NULL;                /* the view column is updatable */
}

References fb(), gettext_noop, IsA, Var::varattno, Var::varlevelsup, and Var::varno.

Referenced by view_cols_are_auto_updatable(), and view_query_is_auto_updatable().

view_cols_are_auto_updatable()

static const char * view_cols_are_auto_updatable ( Query *  viewquery, Bitmapset *  required_cols, Bitmapset **  updatable_cols, char **  non_updatable_col  )

static

Definition at line 2809 of file rewriteHandler.c.

{
    RangeTblRef *rtr;
    AttrNumber  col;
    ListCell   *cell;
 
    /*
     * The caller should have verified that this view is auto-updatable and so
     * there should be a single base relation.
     */
    Assert(list_length(viewquery->jointree->fromlist) == 1);
    rtr = linitial_node(RangeTblRef, viewquery->jointree->fromlist);
 
    /* Initialize the optional return values */
    if (updatable_cols != NULL)
        *updatable_cols = NULL;
    if (non_updatable_col != NULL)
        *non_updatable_col = NULL;
 
    /* Test each view column for updatability */
    col = -FirstLowInvalidHeapAttributeNumber;
    foreach(cell, viewquery->targetList)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(cell);
        const char *col_update_detail;
 
        col++;
        col_update_detail = view_col_is_auto_updatable(rtr, tle);
 
        if (col_update_detail == NULL)
        {
            /* The column is updatable */
            if (updatable_cols != NULL)
                *updatable_cols = bms_add_member(*updatable_cols, col);
        }
        else if (bms_is_member(col, required_cols))
        {
            /* The required column is not updatable */
            if (non_updatable_col != NULL)
                *non_updatable_col = tle->resname;
            return col_update_detail;
        }
    }
 
    return NULL;                /* all the required view columns are updatable */
}

References Assert, bms_add_member(), bms_is_member(), fb(), FirstLowInvalidHeapAttributeNumber, lfirst, linitial_node, list_length(), and view_col_is_auto_updatable().

Referenced by relation_is_updatable(), and rewriteTargetView().

view_has_instead_trigger()

bool view_has_instead_trigger	(	Relation	view,
		CmdType	event,
		List *	mergeActionList
	)

Definition at line 2549 of file rewriteHandler.c.

{
    TriggerDesc *trigDesc = view->trigdesc;
 
    switch (event)
    {
        case CMD_INSERT:
            if (trigDesc && trigDesc->trig_insert_instead_row)
                return true;
            break;
        case CMD_UPDATE:
            if (trigDesc && trigDesc->trig_update_instead_row)
                return true;
            break;
        case CMD_DELETE:
            if (trigDesc && trigDesc->trig_delete_instead_row)
                return true;
            break;
        case CMD_MERGE:
            foreach_node(MergeAction, action, mergeActionList)
            {
                switch (action->commandType)
                {
                    case CMD_INSERT:
                        if (!trigDesc || !trigDesc->trig_insert_instead_row)
                            return false;
                        break;
                    case CMD_UPDATE:
                        if (!trigDesc || !trigDesc->trig_update_instead_row)
                            return false;
                        break;
                    case CMD_DELETE:
                        if (!trigDesc || !trigDesc->trig_delete_instead_row)
                            return false;
                        break;
                    case CMD_NOTHING:
                        /* No trigger required */
                        break;
                    default:
                        elog(ERROR, "unrecognized commandType: %d", action->commandType);
                        break;
                }
            }
            return true;        /* no actions without an INSTEAD OF trigger */
        default:
            elog(ERROR, "unrecognized CmdType: %d", (int) event);
            break;
    }
    return false;
}

References CMD_DELETE, CMD_INSERT, CMD_MERGE, CMD_NOTHING, CMD_UPDATE, elog, ERROR, fb(), foreach_node, and RelationData::trigdesc.

Referenced by CheckValidResultRel(), RewriteQuery(), rewriteTargetView(), and rewriteValuesRTE().

view_query_is_auto_updatable()

const char * view_query_is_auto_updatable	(	Query *	viewquery,
		bool	check_cols
	)

Definition at line 2661 of file rewriteHandler.c.

{
    RangeTblRef *rtr;
    RangeTblEntry *base_rte;
 
    /*----------
     * Check if the view is simply updatable.  According to SQL-92 this means:
     *  - No DISTINCT clause.
     *  - Each TLE is a column reference, and each column appears at most once.
     *  - FROM contains exactly one base relation.
     *  - No GROUP BY or HAVING clauses.
     *  - No set operations (UNION, INTERSECT or EXCEPT).
     *  - No sub-queries in the WHERE clause that reference the target table.
     *
     * We ignore that last restriction since it would be complex to enforce
     * and there isn't any actual benefit to disallowing sub-queries.  (The
     * semantic issues that the standard is presumably concerned about don't
     * arise in Postgres, since any such sub-query will not see any updates
     * executed by the outer query anyway, thanks to MVCC snapshotting.)
     *
     * We also relax the second restriction by supporting part of SQL:1999
     * feature T111, which allows for a mix of updatable and non-updatable
     * columns, provided that an INSERT or UPDATE doesn't attempt to assign to
     * a non-updatable column.
     *
     * In addition we impose these constraints, involving features that are
     * not part of SQL-92:
     *  - No CTEs (WITH clauses).
     *  - No OFFSET or LIMIT clauses (this matches a SQL:2008 restriction).
     *  - No system columns (including whole-row references) in the tlist.
     *  - No window functions in the tlist.
     *  - No set-returning functions in the tlist.
     *
     * Note that we do these checks without recursively expanding the view.
     * If the base relation is a view, we'll recursively deal with it later.
     *----------
     */
    if (viewquery->distinctClause != NIL)
        return gettext_noop("Views containing DISTINCT are not automatically updatable.");
 
    if (viewquery->groupClause != NIL || viewquery->groupingSets)
        return gettext_noop("Views containing GROUP BY are not automatically updatable.");
 
    if (viewquery->havingQual != NULL)
        return gettext_noop("Views containing HAVING are not automatically updatable.");
 
    if (viewquery->setOperations != NULL)
        return gettext_noop("Views containing UNION, INTERSECT, or EXCEPT are not automatically updatable.");
 
    if (viewquery->cteList != NIL)
        return gettext_noop("Views containing WITH are not automatically updatable.");
 
    if (viewquery->limitOffset != NULL || viewquery->limitCount != NULL)
        return gettext_noop("Views containing LIMIT or OFFSET are not automatically updatable.");
 
    /*
     * We must not allow window functions or set returning functions in the
     * targetlist. Otherwise we might end up inserting them into the quals of
     * the main query. We must also check for aggregates in the targetlist in
     * case they appear without a GROUP BY.
     *
     * These restrictions ensure that each row of the view corresponds to a
     * unique row in the underlying base relation.
     */
    if (viewquery->hasAggs)
        return gettext_noop("Views that return aggregate functions are not automatically updatable.");
 
    if (viewquery->hasWindowFuncs)
        return gettext_noop("Views that return window functions are not automatically updatable.");
 
    if (viewquery->hasTargetSRFs)
        return gettext_noop("Views that return set-returning functions are not automatically updatable.");
 
    /*
     * The view query should select from a single base relation, which must be
     * a table or another view.
     */
    if (list_length(viewquery->jointree->fromlist) != 1)
        return gettext_noop("Views that do not select from a single table or view are not automatically updatable.");
 
    rtr = (RangeTblRef *) linitial(viewquery->jointree->fromlist);
    if (!IsA(rtr, RangeTblRef))
        return gettext_noop("Views that do not select from a single table or view are not automatically updatable.");
 
    base_rte = rt_fetch(rtr->rtindex, viewquery->rtable);
    if (base_rte->rtekind != RTE_RELATION ||
        (base_rte->relkind != RELKIND_RELATION &&
         base_rte->relkind != RELKIND_FOREIGN_TABLE &&
         base_rte->relkind != RELKIND_VIEW &&
         base_rte->relkind != RELKIND_PARTITIONED_TABLE))
        return gettext_noop("Views that do not select from a single table or view are not automatically updatable.");
 
    if (base_rte->tablesample)
        return gettext_noop("Views containing TABLESAMPLE are not automatically updatable.");
 
    /*
     * Check that the view has at least one updatable column. This is required
     * for INSERT/UPDATE but not for DELETE.
     */
    if (check_cols)
    {
        ListCell   *cell;
        bool        found;
 
        found = false;
        foreach(cell, viewquery->targetList)
        {
            TargetEntry *tle = (TargetEntry *) lfirst(cell);
 
            if (view_col_is_auto_updatable(rtr, tle) == NULL)
            {
                found = true;
                break;
            }
        }
 
        if (!found)
            return gettext_noop("Views that have no updatable columns are not automatically updatable.");
    }
 
    return NULL;                /* the view is updatable */
}

References fb(), gettext_noop, IsA, lfirst, linitial, list_length(), NIL, rt_fetch, RTE_RELATION, and view_col_is_auto_updatable().

Referenced by ATExecSetRelOptions(), DefineView(), relation_is_updatable(), and rewriteTargetView().