#include "postgres.h"
#include "access/relation.h"
#include "access/xact.h"
#include "catalog/namespace.h"
#include "commands/tablecmds.h"
#include "commands/view.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "parser/analyze.h"
#include "parser/parse_relation.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rewriteHandler.h"
#include "rewrite/rewriteSupport.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"

Include dependency graph for view.c:

Functions
static void	checkViewColumns (TupleDesc newdesc, TupleDesc olddesc)

static ObjectAddress	DefineVirtualRelation (RangeVar relation, List tlist, bool replace, List options, Query viewParse)

static void	DefineViewRules (Oid viewOid, Query *viewParse, bool replace)

ObjectAddress	DefineView (ViewStmt stmt, const char queryString, int stmt_location, int stmt_len)

void	StoreViewQuery (Oid viewOid, Query *viewParse, bool replace)

Function Documentation

◆ checkViewColumns()

static void checkViewColumns	(	TupleDesc	newdesc,
		TupleDesc	olddesc
	)

static

Definition at line 267 of file view.c.

 {
     int         i;
  
     if (newdesc->natts < olddesc->natts)
         ereport(ERROR,
                 (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                  errmsg("cannot drop columns from view")));
  
     for (i = 0; i < olddesc->natts; i++)
     {
         Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
         Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
  
         /* XXX msg not right, but we don't support DROP COL on view anyway */
         if (newattr->attisdropped != oldattr->attisdropped)
             ereport(ERROR,
                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                      errmsg("cannot drop columns from view")));
  
         if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
             ereport(ERROR,
                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                      errmsg("cannot change name of view column \"%s\" to \"%s\"",
                             NameStr(oldattr->attname),
                             NameStr(newattr->attname)),
                      errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
  
         /*
          * We cannot allow type, typmod, or collation to change, since these
          * properties may be embedded in Vars of other views/rules referencing
          * this one.  Other column attributes can be ignored.
          */
         if (newattr->atttypid != oldattr->atttypid ||
             newattr->atttypmod != oldattr->atttypmod)
             ereport(ERROR,
                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                      errmsg("cannot change data type of view column \"%s\" from %s to %s",
                             NameStr(oldattr->attname),
                             format_type_with_typemod(oldattr->atttypid,
                                                      oldattr->atttypmod),
                             format_type_with_typemod(newattr->atttypid,
                                                      newattr->atttypmod))));
  
         /*
          * At this point, attcollations should be both valid or both invalid,
          * so applying get_collation_name unconditionally should be fine.
          */
         if (newattr->attcollation != oldattr->attcollation)
             ereport(ERROR,
                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                      errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
                             NameStr(oldattr->attname),
                             get_collation_name(oldattr->attcollation),
                             get_collation_name(newattr->attcollation))));
     }
  
     /*
      * We ignore the constraint fields.  The new view desc can't have any
      * constraints, and the only ones that could be on the old view are
      * defaults, which we are happy to leave in place.
      */
 }

References ereport, errcode(), errhint(), errmsg(), ERROR, format_type_with_typemod(), get_collation_name(), i, NameStr, TupleDescData::natts, and TupleDescAttr.

Referenced by DefineVirtualRelation().

◆ DefineView()

ObjectAddress DefineView	(	ViewStmt *	stmt,
		const char *	queryString,
		int	stmt_location,
		int	stmt_len
	)

Definition at line 356 of file view.c.

 {
     RawStmt    *rawstmt;
     Query      *viewParse;
     RangeVar   *view;
     ListCell   *cell;
     bool        check_option;
     ObjectAddress address;
  
     /*
      * Run parse analysis to convert the raw parse tree to a Query.  Note this
      * also acquires sufficient locks on the source table(s).
      */
     rawstmt = makeNode(RawStmt);
     rawstmt->stmt = stmt->query;
     rawstmt->stmt_location = stmt_location;
     rawstmt->stmt_len = stmt_len;
  
     viewParse = parse_analyze_fixedparams(rawstmt, queryString, NULL, 0, NULL);
  
     /*
      * The grammar should ensure that the result is a single SELECT Query.
      * However, it doesn't forbid SELECT INTO, so we have to check for that.
      */
     if (!IsA(viewParse, Query))
         elog(ERROR, "unexpected parse analysis result");
     if (viewParse->utilityStmt != NULL &&
         IsA(viewParse->utilityStmt, CreateTableAsStmt))
         ereport(ERROR,
                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                  errmsg("views must not contain SELECT INTO")));
     if (viewParse->commandType != CMD_SELECT)
         elog(ERROR, "unexpected parse analysis result");
  
     /*
      * Check for unsupported cases.  These tests are redundant with ones in
      * DefineQueryRewrite(), but that function will complain about a bogus ON
      * SELECT rule, and we'd rather the message complain about a view.
      */
     if (viewParse->hasModifyingCTE)
         ereport(ERROR,
                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                  errmsg("views must not contain data-modifying statements in WITH")));
  
     /*
      * If the user specified the WITH CHECK OPTION, add it to the list of
      * reloptions.
      */
     if (stmt->withCheckOption == LOCAL_CHECK_OPTION)
         stmt->options = lappend(stmt->options,
                                 makeDefElem("check_option",
                                             (Node *) makeString("local"), -1));
     else if (stmt->withCheckOption == CASCADED_CHECK_OPTION)
         stmt->options = lappend(stmt->options,
                                 makeDefElem("check_option",
                                             (Node *) makeString("cascaded"), -1));
  
     /*
      * Check that the view is auto-updatable if WITH CHECK OPTION was
      * specified.
      */
     check_option = false;
  
     foreach(cell, stmt->options)
     {
         DefElem    *defel = (DefElem *) lfirst(cell);
  
         if (strcmp(defel->defname, "check_option") == 0)
             check_option = true;
     }
  
     /*
      * If the check option is specified, look to see if the view is actually
      * auto-updatable or not.
      */
     if (check_option)
     {
         const char *view_updatable_error =
             view_query_is_auto_updatable(viewParse, true);
  
         if (view_updatable_error)
             ereport(ERROR,
                     (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                      errmsg("WITH CHECK OPTION is supported only on automatically updatable views"),
                      errhint("%s", _(view_updatable_error))));
     }
  
     /*
      * If a list of column names was given, run through and insert these into
      * the actual query tree. - thomas 2000-03-08
      */
     if (stmt->aliases != NIL)
     {
         ListCell   *alist_item = list_head(stmt->aliases);
         ListCell   *targetList;
  
         foreach(targetList, viewParse->targetList)
         {
             TargetEntry *te = lfirst_node(TargetEntry, targetList);
  
             /* junk columns don't get aliases */
             if (te->resjunk)
                 continue;
             te->resname = pstrdup(strVal(lfirst(alist_item)));
             alist_item = lnext(stmt->aliases, alist_item);
             if (alist_item == NULL)
                 break;          /* done assigning aliases */
         }
  
         if (alist_item != NULL)
             ereport(ERROR,
                     (errcode(ERRCODE_SYNTAX_ERROR),
                      errmsg("CREATE VIEW specifies more column "
                             "names than columns")));
     }
  
     /* Unlogged views are not sensible. */
     if (stmt->view->relpersistence == RELPERSISTENCE_UNLOGGED)
         ereport(ERROR,
                 (errcode(ERRCODE_SYNTAX_ERROR),
                  errmsg("views cannot be unlogged because they do not have storage")));
  
     /*
      * If the user didn't explicitly ask for a temporary view, check whether
      * we need one implicitly.  We allow TEMP to be inserted automatically as
      * long as the CREATE command is consistent with that --- no explicit
      * schema name.
      */
     view = copyObject(stmt->view);  /* don't corrupt original command */
     if (view->relpersistence == RELPERSISTENCE_PERMANENT
         && isQueryUsingTempRelation(viewParse))
     {
         view->relpersistence = RELPERSISTENCE_TEMP;
         ereport(NOTICE,
                 (errmsg("view \"%s\" will be a temporary view",
                         view->relname)));
     }
  
     /*
      * Create the view relation
      *
      * NOTE: if it already exists and replace is false, the xact will be
      * aborted.
      */
     address = DefineVirtualRelation(view, viewParse->targetList,
                                     stmt->replace, stmt->options, viewParse);
  
     return address;
 }

References _, CASCADED_CHECK_OPTION, CMD_SELECT, Query::commandType, copyObject, DefineVirtualRelation(), DefElem::defname, elog, ereport, errcode(), errhint(), errmsg(), ERROR, IsA, isQueryUsingTempRelation(), lappend(), lfirst, lfirst_node, list_head(), lnext(), LOCAL_CHECK_OPTION, makeDefElem(), makeNode, makeString(), NIL, NOTICE, parse_analyze_fixedparams(), pstrdup(), RangeVar::relname, RangeVar::relpersistence, RawStmt::stmt, stmt, RawStmt::stmt_len, RawStmt::stmt_location, strVal, Query::targetList, Query::utilityStmt, and view_query_is_auto_updatable().

Referenced by ProcessUtilitySlow().

◆ DefineViewRules()

static void DefineViewRules	(	Oid	viewOid,
		Query *	viewParse,
		bool	replace
	)

static

Definition at line 332 of file view.c.

 {
     /*
      * Set up the ON SELECT rule.  Since the query has already been through
      * parse analysis, we use DefineQueryRewrite() directly.
      */
     DefineQueryRewrite(pstrdup(ViewSelectRuleName),
                        viewOid,
                        NULL,
                        CMD_SELECT,
                        true,
                        replace,
                        list_make1(viewParse));
  
     /*
      * Someday: automatic ON INSERT, etc
      */
 }

References CMD_SELECT, DefineQueryRewrite(), list_make1, pstrdup(), and ViewSelectRuleName.

Referenced by StoreViewQuery().

◆ DefineVirtualRelation()

static ObjectAddress DefineVirtualRelation	(	RangeVar *	relation,
		List *	tlist,
		bool	replace,
		List *	options,
		Query *	viewParse
	)

static

Definition at line 45 of file view.c.

 {
     Oid         viewOid;
     LOCKMODE    lockmode;
     CreateStmt *createStmt = makeNode(CreateStmt);
     List       *attrList;
     ListCell   *t;
  
     /*
      * create a list of ColumnDef nodes based on the names and types of the
      * (non-junk) targetlist items from the view's SELECT list.
      */
     attrList = NIL;
     foreach(t, tlist)
     {
         TargetEntry *tle = (TargetEntry *) lfirst(t);
  
         if (!tle->resjunk)
         {
             ColumnDef  *def = makeColumnDef(tle->resname,
                                             exprType((Node *) tle->expr),
                                             exprTypmod((Node *) tle->expr),
                                             exprCollation((Node *) tle->expr));
  
             /*
              * It's possible that the column is of a collatable type but the
              * collation could not be resolved, so double-check.
              */
             if (type_is_collatable(exprType((Node *) tle->expr)))
             {
                 if (!OidIsValid(def->collOid))
                     ereport(ERROR,
                             (errcode(ERRCODE_INDETERMINATE_COLLATION),
                              errmsg("could not determine which collation to use for view column \"%s\"",
                                     def->colname),
                              errhint("Use the COLLATE clause to set the collation explicitly.")));
             }
             else
                 Assert(!OidIsValid(def->collOid));
  
             attrList = lappend(attrList, def);
         }
     }
  
     /*
      * Look up, check permissions on, and lock the creation namespace; also
      * check for a preexisting view with the same name.  This will also set
      * relation->relpersistence to RELPERSISTENCE_TEMP if the selected
      * namespace is temporary.
      */
     lockmode = replace ? AccessExclusiveLock : NoLock;
     (void) RangeVarGetAndCheckCreationNamespace(relation, lockmode, &viewOid);
  
     if (OidIsValid(viewOid) && replace)
     {
         Relation    rel;
         TupleDesc   descriptor;
         List       *atcmds = NIL;
         AlterTableCmd *atcmd;
         ObjectAddress address;
  
         /* Relation is already locked, but we must build a relcache entry. */
         rel = relation_open(viewOid, NoLock);
  
         /* Make sure it *is* a view. */
         if (rel->rd_rel->relkind != RELKIND_VIEW)
             ereport(ERROR,
                     (errcode(ERRCODE_WRONG_OBJECT_TYPE),
                      errmsg("\"%s\" is not a view",
                             RelationGetRelationName(rel))));
  
         /* Also check it's not in use already */
         CheckTableNotInUse(rel, "CREATE OR REPLACE VIEW");
  
         /*
          * Due to the namespace visibility rules for temporary objects, we
          * should only end up replacing a temporary view with another
          * temporary view, and similarly for permanent views.
          */
         Assert(relation->relpersistence == rel->rd_rel->relpersistence);
  
         /*
          * Create a tuple descriptor to compare against the existing view, and
          * verify that the old column list is an initial prefix of the new
          * column list.
          */
         descriptor = BuildDescForRelation(attrList);
         checkViewColumns(descriptor, rel->rd_att);
  
         /*
          * If new attributes have been added, we must add pg_attribute entries
          * for them.  It is convenient (although overkill) to use the ALTER
          * TABLE ADD COLUMN infrastructure for this.
          *
          * Note that we must do this before updating the query for the view,
          * since the rules system requires that the correct view columns be in
          * place when defining the new rules.
          *
          * Also note that ALTER TABLE doesn't run parse transformation on
          * AT_AddColumnToView commands.  The ColumnDef we supply must be ready
          * to execute as-is.
          */
         if (list_length(attrList) > rel->rd_att->natts)
         {
             ListCell   *c;
             int         skip = rel->rd_att->natts;
  
             foreach(c, attrList)
             {
                 if (skip > 0)
                 {
                     skip--;
                     continue;
                 }
                 atcmd = makeNode(AlterTableCmd);
                 atcmd->subtype = AT_AddColumnToView;
                 atcmd->def = (Node *) lfirst(c);
                 atcmds = lappend(atcmds, atcmd);
             }
  
             /* EventTriggerAlterTableStart called by ProcessUtilitySlow */
             AlterTableInternal(viewOid, atcmds, true);
  
             /* Make the new view columns visible */
             CommandCounterIncrement();
         }
  
         /*
          * Update the query for the view.
          *
          * Note that we must do this before updating the view options, because
          * the new options may not be compatible with the old view query (for
          * example if we attempt to add the WITH CHECK OPTION, we require that
          * the new view be automatically updatable, but the old view may not
          * have been).
          */
         StoreViewQuery(viewOid, viewParse, replace);
  
         /* Make the new view query visible */
         CommandCounterIncrement();
  
         /*
          * Update the view's options.
          *
          * The new options list replaces the existing options list, even if
          * it's empty.
          */
         atcmd = makeNode(AlterTableCmd);
         atcmd->subtype = AT_ReplaceRelOptions;
         atcmd->def = (Node *) options;
         atcmds = list_make1(atcmd);
  
         /* EventTriggerAlterTableStart called by ProcessUtilitySlow */
         AlterTableInternal(viewOid, atcmds, true);
  
         /*
          * There is very little to do here to update the view's dependencies.
          * Most view-level dependency relationships, such as those on the
          * owner, schema, and associated composite type, aren't changing.
          * Because we don't allow changing type or collation of an existing
          * view column, those dependencies of the existing columns don't
          * change either, while the AT_AddColumnToView machinery took care of
          * adding such dependencies for new view columns.  The dependencies of
          * the view's query could have changed arbitrarily, but that was dealt
          * with inside StoreViewQuery.  What remains is only to check that
          * view replacement is allowed when we're creating an extension.
          */
         ObjectAddressSet(address, RelationRelationId, viewOid);
  
         recordDependencyOnCurrentExtension(&address, true);
  
         /*
          * Seems okay, so return the OID of the pre-existing view.
          */
         relation_close(rel, NoLock);    /* keep the lock! */
  
         return address;
     }
     else
     {
         ObjectAddress address;
  
         /*
          * Set the parameters for keys/inheritance etc. All of these are
          * uninteresting for views...
          */
         createStmt->relation = relation;
         createStmt->tableElts = attrList;
         createStmt->inhRelations = NIL;
         createStmt->constraints = NIL;
         createStmt->options = options;
         createStmt->oncommit = ONCOMMIT_NOOP;
         createStmt->tablespacename = NULL;
         createStmt->if_not_exists = false;
  
         /*
          * Create the relation (this will error out if there's an existing
          * view, so we don't need more code to complain if "replace" is
          * false).
          */
         address = DefineRelation(createStmt, RELKIND_VIEW, InvalidOid, NULL,
                                  NULL);
         Assert(address.objectId != InvalidOid);
  
         /* Make the new view relation visible */
         CommandCounterIncrement();
  
         /* Store the query for the view */
         StoreViewQuery(address.objectId, viewParse, replace);
  
         return address;
     }
 }

References AccessExclusiveLock, AlterTableInternal(), Assert, AT_AddColumnToView, AT_ReplaceRelOptions, BuildDescForRelation(), CheckTableNotInUse(), checkViewColumns(), ColumnDef::collOid, ColumnDef::colname, CommandCounterIncrement(), CreateStmt::constraints, AlterTableCmd::def, DefineRelation(), ereport, errcode(), errhint(), errmsg(), ERROR, TargetEntry::expr, exprCollation(), exprType(), exprTypmod(), CreateStmt::if_not_exists, CreateStmt::inhRelations, InvalidOid, lappend(), lfirst, list_length(), list_make1, makeColumnDef(), makeNode, TupleDescData::natts, NIL, NoLock, ObjectAddressSet, ObjectAddress::objectId, OidIsValid, CreateStmt::oncommit, ONCOMMIT_NOOP, options, CreateStmt::options, RangeVarGetAndCheckCreationNamespace(), RelationData::rd_att, RelationData::rd_rel, recordDependencyOnCurrentExtension(), CreateStmt::relation, relation_close(), relation_open(), RelationGetRelationName, RangeVar::relpersistence, skip, StoreViewQuery(), AlterTableCmd::subtype, CreateStmt::tableElts, CreateStmt::tablespacename, and type_is_collatable().

Referenced by DefineView().

◆ StoreViewQuery()

void StoreViewQuery	(	Oid	viewOid,
		Query *	viewParse,
		bool	replace
	)

Definition at line 511 of file view.c.

 {
     /*
      * Now create the rules associated with the view.
      */
     DefineViewRules(viewOid, viewParse, replace);
 }

References DefineViewRules().

Referenced by create_ctas_internal(), and DefineVirtualRelation().

Functions

Function Documentation

◆ checkViewColumns()

◆ DefineView()

◆ DefineViewRules()

◆ DefineVirtualRelation()

◆ StoreViewQuery()