equivclass.c File Reference

#include "postgres.h"
#include <limits.h>
#include "access/stratnum.h"
#include "catalog/pg_type.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/appendinfo.h"
#include "optimizer/clauses.h"
#include "optimizer/optimizer.h"
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "optimizer/planmain.h"
#include "optimizer/restrictinfo.h"
#include "rewrite/rewriteManip.h"
#include "utils/lsyscache.h"

Include dependency graph for equivclass.c:

Go to the source code of this file.

Functions
static EquivalenceMember *	add_eq_member (EquivalenceClass *ec, Expr *expr, Relids relids, JoinDomain *jdomain, EquivalenceMember *parent, Oid datatype)
static bool	is_exprlist_member (Expr *node, List *exprs)
static void	generate_base_implied_equalities_const (PlannerInfo *root, EquivalenceClass *ec)
static void	generate_base_implied_equalities_no_const (PlannerInfo *root, EquivalenceClass *ec)
static void	generate_base_implied_equalities_broken (PlannerInfo *root, EquivalenceClass *ec)
static List *	generate_join_implied_equalities_normal (PlannerInfo *root, EquivalenceClass *ec, Relids join_relids, Relids outer_relids, Relids inner_relids)
static List *	generate_join_implied_equalities_broken (PlannerInfo *root, EquivalenceClass *ec, Relids nominal_join_relids, Relids outer_relids, Relids nominal_inner_relids, RelOptInfo *inner_rel)
static Oid	select_equality_operator (EquivalenceClass *ec, Oid lefttype, Oid righttype)
static RestrictInfo *	create_join_clause (PlannerInfo *root, EquivalenceClass *ec, Oid opno, EquivalenceMember *leftem, EquivalenceMember *rightem, EquivalenceClass *parent_ec)
static bool	reconsider_outer_join_clause (PlannerInfo *root, OuterJoinClauseInfo *ojcinfo, bool outer_on_left)
static bool	reconsider_full_join_clause (PlannerInfo *root, OuterJoinClauseInfo *ojcinfo)
static JoinDomain *	find_join_domain (PlannerInfo *root, Relids relids)
static Bitmapset *	get_eclass_indexes_for_relids (PlannerInfo *root, Relids relids)
static Bitmapset *	get_common_eclass_indexes (PlannerInfo *root, Relids relids1, Relids relids2)
bool	process_equivalence (PlannerInfo *root, RestrictInfo **p_restrictinfo, JoinDomain *jdomain)
Expr *	canonicalize_ec_expression (Expr *expr, Oid req_type, Oid req_collation)
EquivalenceClass *	get_eclass_for_sort_expr (PlannerInfo *root, Expr *expr, List *opfamilies, Oid opcintype, Oid collation, Index sortref, Relids rel, bool create_it)
EquivalenceMember *	find_ec_member_matching_expr (EquivalenceClass *ec, Expr *expr, Relids relids)
EquivalenceMember *	find_computable_ec_member (PlannerInfo *root, EquivalenceClass *ec, List *exprs, Relids relids, bool require_parallel_safe)
bool	relation_can_be_sorted_early (PlannerInfo *root, RelOptInfo *rel, EquivalenceClass *ec, bool require_parallel_safe)
void	generate_base_implied_equalities (PlannerInfo *root)
List *	generate_join_implied_equalities (PlannerInfo *root, Relids join_relids, Relids outer_relids, RelOptInfo *inner_rel, SpecialJoinInfo *sjinfo)
List *	generate_join_implied_equalities_for_ecs (PlannerInfo *root, List *eclasses, Relids join_relids, Relids outer_relids, RelOptInfo *inner_rel)
void	reconsider_outer_join_clauses (PlannerInfo *root)
bool	exprs_known_equal (PlannerInfo *root, Node *item1, Node *item2)
EquivalenceClass *	match_eclasses_to_foreign_key_col (PlannerInfo *root, ForeignKeyOptInfo *fkinfo, int colno)
RestrictInfo *	find_derived_clause_for_ec_member (EquivalenceClass *ec, EquivalenceMember *em)
void	add_child_rel_equivalences (PlannerInfo *root, AppendRelInfo *appinfo, RelOptInfo *parent_rel, RelOptInfo *child_rel)
void	add_child_join_rel_equivalences (PlannerInfo *root, int nappinfos, AppendRelInfo **appinfos, RelOptInfo *parent_joinrel, RelOptInfo *child_joinrel)
void	add_setop_child_rel_equivalences (PlannerInfo *root, RelOptInfo *child_rel, List *child_tlist, List *setop_pathkeys)
List *	generate_implied_equalities_for_column (PlannerInfo *root, RelOptInfo *rel, ec_matches_callback_type callback, void *callback_arg, Relids prohibited_rels)
bool	have_relevant_eclass_joinclause (PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2)
bool	has_relevant_eclass_joinclause (PlannerInfo *root, RelOptInfo *rel1)
bool	eclass_useful_for_merging (PlannerInfo *root, EquivalenceClass *eclass, RelOptInfo *rel)
bool	is_redundant_derived_clause (RestrictInfo *rinfo, List *clauselist)
bool	is_redundant_with_indexclauses (RestrictInfo *rinfo, List *indexclauses)

Function Documentation

add_child_join_rel_equivalences()

void add_child_join_rel_equivalences	(	PlannerInfo *	root,
		int	nappinfos,
		AppendRelInfo **	appinfos,
		RelOptInfo *	parent_joinrel,
		RelOptInfo *	child_joinrel
	)

Definition at line 2769 of file equivclass.c.

{
    Relids      top_parent_relids = child_joinrel->top_parent_relids;
    Relids      child_relids = child_joinrel->relids;
    Bitmapset  *matching_ecs;
    MemoryContext oldcontext;
    int         i;
 
    Assert(IS_JOIN_REL(child_joinrel) && IS_JOIN_REL(parent_joinrel));
 
    /* We need consider only ECs that mention the parent joinrel */
    matching_ecs = get_eclass_indexes_for_relids(root, top_parent_relids);
 
    /*
     * If we're being called during GEQO join planning, we still have to
     * create any new EC members in the main planner context, to avoid having
     * a corrupt EC data structure after the GEQO context is reset.  This is
     * problematic since we'll leak memory across repeated GEQO cycles.  For
     * now, though, bloat is better than crash.  If it becomes a real issue
     * we'll have to do something to avoid generating duplicate EC members.
     */
    oldcontext = MemoryContextSwitchTo(root->planner_cxt);
 
    i = -1;
    while ((i = bms_next_member(matching_ecs, i)) >= 0)
    {
        EquivalenceClass *cur_ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
        int         num_members;
 
        /*
         * If this EC contains a volatile expression, then generating child
         * EMs would be downright dangerous, so skip it.  We rely on a
         * volatile EC having only one EM.
         */
        if (cur_ec->ec_has_volatile)
            continue;
 
        /* Sanity check on get_eclass_indexes_for_relids result */
        Assert(bms_overlap(top_parent_relids, cur_ec->ec_relids));
 
        /*
         * We don't use foreach() here because there's no point in scanning
         * newly-added child members, so we can stop after the last
         * pre-existing EC member.
         */
        num_members = list_length(cur_ec->ec_members);
        for (int pos = 0; pos < num_members; pos++)
        {
            EquivalenceMember *cur_em = (EquivalenceMember *) list_nth(cur_ec->ec_members, pos);
 
            if (cur_em->em_is_const)
                continue;       /* ignore consts here */
 
            /*
             * We consider only original EC members here, not
             * already-transformed child members.
             */
            if (cur_em->em_is_child)
                continue;       /* ignore children here */
 
            /*
             * We may ignore expressions that reference a single baserel,
             * because add_child_rel_equivalences should have handled them.
             */
            if (bms_membership(cur_em->em_relids) != BMS_MULTIPLE)
                continue;
 
            /* Does this member reference child's topmost parent rel? */
            if (bms_overlap(cur_em->em_relids, top_parent_relids))
            {
                /* Yes, generate transformed child version */
                Expr       *child_expr;
                Relids      new_relids;
 
                if (parent_joinrel->reloptkind == RELOPT_JOINREL)
                {
                    /* Simple single-level transformation */
                    child_expr = (Expr *)
                        adjust_appendrel_attrs(root,
                                               (Node *) cur_em->em_expr,
                                               nappinfos, appinfos);
                }
                else
                {
                    /* Must do multi-level transformation */
                    Assert(parent_joinrel->reloptkind == RELOPT_OTHER_JOINREL);
                    child_expr = (Expr *)
                        adjust_appendrel_attrs_multilevel(root,
                                                          (Node *) cur_em->em_expr,
                                                          child_joinrel,
                                                          child_joinrel->top_parent);
                }
 
                /*
                 * Transform em_relids to match.  Note we do *not* do
                 * pull_varnos(child_expr) here, as for example the
                 * transformation might have substituted a constant, but we
                 * don't want the child member to be marked as constant.
                 */
                new_relids = bms_difference(cur_em->em_relids,
                                            top_parent_relids);
                new_relids = bms_add_members(new_relids, child_relids);
 
                (void) add_eq_member(cur_ec, child_expr, new_relids,
                                     cur_em->em_jdomain,
                                     cur_em, cur_em->em_datatype);
            }
        }
    }
 
    MemoryContextSwitchTo(oldcontext);
}

References add_eq_member(), adjust_appendrel_attrs(), adjust_appendrel_attrs_multilevel(), Assert, bms_add_members(), bms_difference(), bms_membership(), BMS_MULTIPLE, bms_next_member(), bms_overlap(), EquivalenceClass::ec_has_volatile, EquivalenceClass::ec_members, EquivalenceClass::ec_relids, EquivalenceMember::em_datatype, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_is_const, EquivalenceMember::em_jdomain, EquivalenceMember::em_relids, get_eclass_indexes_for_relids(), i, IS_JOIN_REL, list_length(), list_nth(), MemoryContextSwitchTo(), RelOptInfo::relids, RELOPT_JOINREL, RELOPT_OTHER_JOINREL, RelOptInfo::reloptkind, root, and RelOptInfo::top_parent_relids.

Referenced by build_child_join_rel().

add_child_rel_equivalences()

void add_child_rel_equivalences	(	PlannerInfo *	root,
		AppendRelInfo *	appinfo,
		RelOptInfo *	parent_rel,
		RelOptInfo *	child_rel
	)

Definition at line 2647 of file equivclass.c.

{
    Relids      top_parent_relids = child_rel->top_parent_relids;
    Relids      child_relids = child_rel->relids;
    int         i;
 
    /*
     * EC merging should be complete already, so we can use the parent rel's
     * eclass_indexes to avoid searching all of root->eq_classes.
     */
    Assert(root->ec_merging_done);
    Assert(IS_SIMPLE_REL(parent_rel));
 
    i = -1;
    while ((i = bms_next_member(parent_rel->eclass_indexes, i)) >= 0)
    {
        EquivalenceClass *cur_ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
        int         num_members;
 
        /*
         * If this EC contains a volatile expression, then generating child
         * EMs would be downright dangerous, so skip it.  We rely on a
         * volatile EC having only one EM.
         */
        if (cur_ec->ec_has_volatile)
            continue;
 
        /* Sanity check eclass_indexes only contain ECs for parent_rel */
        Assert(bms_is_subset(top_parent_relids, cur_ec->ec_relids));
 
        /*
         * We don't use foreach() here because there's no point in scanning
         * newly-added child members, so we can stop after the last
         * pre-existing EC member.
         */
        num_members = list_length(cur_ec->ec_members);
        for (int pos = 0; pos < num_members; pos++)
        {
            EquivalenceMember *cur_em = (EquivalenceMember *) list_nth(cur_ec->ec_members, pos);
 
            if (cur_em->em_is_const)
                continue;       /* ignore consts here */
 
            /*
             * We consider only original EC members here, not
             * already-transformed child members.  Otherwise, if some original
             * member expression references more than one appendrel, we'd get
             * an O(N^2) explosion of useless derived expressions for
             * combinations of children.  (But add_child_join_rel_equivalences
             * may add targeted combinations for partitionwise-join purposes.)
             */
            if (cur_em->em_is_child)
                continue;       /* ignore children here */
 
            /*
             * Consider only members that reference and can be computed at
             * child's topmost parent rel.  In particular we want to exclude
             * parent-rel Vars that have nonempty varnullingrels.  Translating
             * those might fail, if the transformed expression wouldn't be a
             * simple Var; and in any case it wouldn't produce a member that
             * has any use in creating plans for the child rel.
             */
            if (bms_is_subset(cur_em->em_relids, top_parent_relids) &&
                !bms_is_empty(cur_em->em_relids))
            {
                /* OK, generate transformed child version */
                Expr       *child_expr;
                Relids      new_relids;
 
                if (parent_rel->reloptkind == RELOPT_BASEREL)
                {
                    /* Simple single-level transformation */
                    child_expr = (Expr *)
                        adjust_appendrel_attrs(root,
                                               (Node *) cur_em->em_expr,
                                               1, &appinfo);
                }
                else
                {
                    /* Must do multi-level transformation */
                    child_expr = (Expr *)
                        adjust_appendrel_attrs_multilevel(root,
                                                          (Node *) cur_em->em_expr,
                                                          child_rel,
                                                          child_rel->top_parent);
                }
 
                /*
                 * Transform em_relids to match.  Note we do *not* do
                 * pull_varnos(child_expr) here, as for example the
                 * transformation might have substituted a constant, but we
                 * don't want the child member to be marked as constant.
                 */
                new_relids = bms_difference(cur_em->em_relids,
                                            top_parent_relids);
                new_relids = bms_add_members(new_relids, child_relids);
 
                (void) add_eq_member(cur_ec, child_expr, new_relids,
                                     cur_em->em_jdomain,
                                     cur_em, cur_em->em_datatype);
 
                /* Record this EC index for the child rel */
                child_rel->eclass_indexes = bms_add_member(child_rel->eclass_indexes, i);
            }
        }
    }
}

References add_eq_member(), adjust_appendrel_attrs(), adjust_appendrel_attrs_multilevel(), Assert, bms_add_member(), bms_add_members(), bms_difference(), bms_is_empty, bms_is_subset(), bms_next_member(), EquivalenceClass::ec_has_volatile, EquivalenceClass::ec_members, EquivalenceClass::ec_relids, RelOptInfo::eclass_indexes, EquivalenceMember::em_datatype, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_is_const, EquivalenceMember::em_jdomain, EquivalenceMember::em_relids, i, IS_SIMPLE_REL, list_length(), list_nth(), RelOptInfo::relids, RELOPT_BASEREL, RelOptInfo::reloptkind, root, and RelOptInfo::top_parent_relids.

Referenced by set_append_rel_size().

add_eq_member()

static EquivalenceMember * add_eq_member ( EquivalenceClass *  ec, Expr *  expr, Relids  relids, JoinDomain *  jdomain, EquivalenceMember *  parent, Oid  datatype  )

static

Definition at line 517 of file equivclass.c.

{
    EquivalenceMember *em = makeNode(EquivalenceMember);
 
    em->em_expr = expr;
    em->em_relids = relids;
    em->em_is_const = false;
    em->em_is_child = (parent != NULL);
    em->em_datatype = datatype;
    em->em_jdomain = jdomain;
    em->em_parent = parent;
 
    if (bms_is_empty(relids))
    {
        /*
         * No Vars, assume it's a pseudoconstant.  This is correct for entries
         * generated from process_equivalence(), because a WHERE clause can't
         * contain aggregates or SRFs, and non-volatility was checked before
         * process_equivalence() ever got called.  But
         * get_eclass_for_sort_expr() has to work harder.  We put the tests
         * there not here to save cycles in the equivalence case.
         */
        Assert(!parent);
        em->em_is_const = true;
        ec->ec_has_const = true;
        /* it can't affect ec_relids */
    }
    else if (!parent)           /* child members don't add to ec_relids */
    {
        ec->ec_relids = bms_add_members(ec->ec_relids, relids);
    }
    ec->ec_members = lappend(ec->ec_members, em);
 
    return em;
}

References Assert, bms_add_members(), bms_is_empty, EquivalenceClass::ec_has_const, EquivalenceClass::ec_members, EquivalenceClass::ec_relids, EquivalenceMember::em_datatype, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_is_const, EquivalenceMember::em_jdomain, EquivalenceMember::em_relids, lappend(), and makeNode.

Referenced by add_child_join_rel_equivalences(), add_child_rel_equivalences(), add_setop_child_rel_equivalences(), get_eclass_for_sort_expr(), and process_equivalence().

add_setop_child_rel_equivalences()

void add_setop_child_rel_equivalences	(	PlannerInfo *	root,
		RelOptInfo *	child_rel,
		List *	child_tlist,
		List *	setop_pathkeys
	)

Definition at line 2899 of file equivclass.c.

{
    ListCell   *lc;
    ListCell   *lc2 = list_head(setop_pathkeys);
 
    foreach(lc, child_tlist)
    {
        TargetEntry *tle = lfirst_node(TargetEntry, lc);
        EquivalenceMember *parent_em;
        PathKey    *pk;
 
        if (tle->resjunk)
            continue;
 
        if (lc2 == NULL)
            elog(ERROR, "too few pathkeys for set operation");
 
        pk = lfirst_node(PathKey, lc2);
        parent_em = linitial(pk->pk_eclass->ec_members);
 
        /*
         * We can safely pass the parent member as the first member in the
         * ec_members list as this is added first in generate_union_paths,
         * likewise, the JoinDomain can be that of the initial member of the
         * Pathkey's EquivalenceClass.
         */
        add_eq_member(pk->pk_eclass,
                      tle->expr,
                      child_rel->relids,
                      parent_em->em_jdomain,
                      parent_em,
                      exprType((Node *) tle->expr));
 
        lc2 = lnext(setop_pathkeys, lc2);
    }
 
    /*
     * transformSetOperationStmt() ensures that the targetlist never contains
     * any resjunk columns, so all eclasses that exist in 'root' must have
     * received a new member in the loop above.  Add them to the child_rel's
     * eclass_indexes.
     */
    child_rel->eclass_indexes = bms_add_range(child_rel->eclass_indexes, 0,
                                              list_length(root->eq_classes) - 1);
}

References add_eq_member(), bms_add_range(), RelOptInfo::eclass_indexes, elog, EquivalenceMember::em_jdomain, ERROR, TargetEntry::expr, exprType(), lfirst_node, linitial, list_head(), list_length(), lnext(), RelOptInfo::relids, and root.

Referenced by build_setop_child_paths().

canonicalize_ec_expression()

Expr* canonicalize_ec_expression	(	Expr *	expr,
		Oid	req_type,
		Oid	req_collation
	)

Definition at line 472 of file equivclass.c.

{
    Oid         expr_type = exprType((Node *) expr);
 
    /*
     * For a polymorphic-input-type opclass, just keep the same exposed type.
     * RECORD opclasses work like polymorphic-type ones for this purpose.
     */
    if (IsPolymorphicType(req_type) || req_type == RECORDOID)
        req_type = expr_type;
 
    /*
     * No work if the expression exposes the right type/collation already.
     */
    if (expr_type != req_type ||
        exprCollation((Node *) expr) != req_collation)
    {
        /*
         * If we have to change the type of the expression, set typmod to -1,
         * since the new type may not have the same typmod interpretation.
         * When we only have to change collation, preserve the exposed typmod.
         */
        int32       req_typmod;
 
        if (expr_type != req_type)
            req_typmod = -1;
        else
            req_typmod = exprTypmod((Node *) expr);
 
        /*
         * Use applyRelabelType so that we preserve const-flatness.  This is
         * important since eval_const_expressions has already been applied.
         */
        expr = (Expr *) applyRelabelType((Node *) expr,
                                         req_type, req_typmod, req_collation,
                                         COERCE_IMPLICIT_CAST, -1, false);
    }
 
    return expr;
}

References applyRelabelType(), COERCE_IMPLICIT_CAST, exprCollation(), exprType(), and exprTypmod().

Referenced by convert_subquery_pathkeys(), get_eclass_for_sort_expr(), and process_equivalence().

create_join_clause()

static RestrictInfo * create_join_clause ( PlannerInfo *  root, EquivalenceClass *  ec, Oid  opno, EquivalenceMember *  leftem, EquivalenceMember *  rightem, EquivalenceClass *  parent_ec  )

static

Definition at line 1824 of file equivclass.c.

{
    RestrictInfo *rinfo;
    RestrictInfo *parent_rinfo = NULL;
    ListCell   *lc;
    MemoryContext oldcontext;
 
    /*
     * Search to see if we already built a RestrictInfo for this pair of
     * EquivalenceMembers.  We can use either original source clauses or
     * previously-derived clauses, and a commutator clause is acceptable.
     *
     * We used to verify that opno matches, but that seems redundant: even if
     * it's not identical, it'd better have the same effects, or the operator
     * families we're using are broken.
     */
    foreach(lc, ec->ec_sources)
    {
        rinfo = (RestrictInfo *) lfirst(lc);
        if (rinfo->left_em == leftem &&
            rinfo->right_em == rightem &&
            rinfo->parent_ec == parent_ec)
            return rinfo;
        if (rinfo->left_em == rightem &&
            rinfo->right_em == leftem &&
            rinfo->parent_ec == parent_ec)
            return rinfo;
    }
 
    foreach(lc, ec->ec_derives)
    {
        rinfo = (RestrictInfo *) lfirst(lc);
        if (rinfo->left_em == leftem &&
            rinfo->right_em == rightem &&
            rinfo->parent_ec == parent_ec)
            return rinfo;
        if (rinfo->left_em == rightem &&
            rinfo->right_em == leftem &&
            rinfo->parent_ec == parent_ec)
            return rinfo;
    }
 
    /*
     * Not there, so build it, in planner context so we can re-use it. (Not
     * important in normal planning, but definitely so in GEQO.)
     */
    oldcontext = MemoryContextSwitchTo(root->planner_cxt);
 
    /*
     * If either EM is a child, recursively create the corresponding
     * parent-to-parent clause, so that we can duplicate its rinfo_serial.
     */
    if (leftem->em_is_child || rightem->em_is_child)
    {
        EquivalenceMember *leftp = leftem->em_parent ? leftem->em_parent : leftem;
        EquivalenceMember *rightp = rightem->em_parent ? rightem->em_parent : rightem;
 
        parent_rinfo = create_join_clause(root, ec, opno,
                                          leftp, rightp,
                                          parent_ec);
    }
 
    rinfo = build_implied_join_equality(root,
                                        opno,
                                        ec->ec_collation,
                                        leftem->em_expr,
                                        rightem->em_expr,
                                        bms_union(leftem->em_relids,
                                                  rightem->em_relids),
                                        ec->ec_min_security);
 
    /*
     * If either EM is a child, force the clause's clause_relids to include
     * the relid(s) of the child rel.  In normal cases it would already, but
     * not if we are considering appendrel child relations with pseudoconstant
     * translated variables (i.e., UNION ALL sub-selects with constant output
     * items).  We must do this so that join_clause_is_movable_into() will
     * think that the clause should be evaluated at the correct place.
     */
    if (leftem->em_is_child)
        rinfo->clause_relids = bms_add_members(rinfo->clause_relids,
                                               leftem->em_relids);
    if (rightem->em_is_child)
        rinfo->clause_relids = bms_add_members(rinfo->clause_relids,
                                               rightem->em_relids);
 
    /* If it's a child clause, copy the parent's rinfo_serial */
    if (parent_rinfo)
        rinfo->rinfo_serial = parent_rinfo->rinfo_serial;
 
    /* Mark the clause as redundant, or not */
    rinfo->parent_ec = parent_ec;
 
    /*
     * We know the correct values for left_ec/right_ec, ie this particular EC,
     * so we can just set them directly instead of forcing another lookup.
     */
    rinfo->left_ec = ec;
    rinfo->right_ec = ec;
 
    /* Mark it as usable with these EMs */
    rinfo->left_em = leftem;
    rinfo->right_em = rightem;
    /* and save it for possible re-use */
    ec->ec_derives = lappend(ec->ec_derives, rinfo);
 
    MemoryContextSwitchTo(oldcontext);
 
    return rinfo;
}

References bms_add_members(), bms_union(), build_implied_join_equality(), EquivalenceClass::ec_collation, EquivalenceClass::ec_derives, EquivalenceClass::ec_min_security, EquivalenceClass::ec_sources, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_relids, lappend(), lfirst, MemoryContextSwitchTo(), RestrictInfo::rinfo_serial, and root.

Referenced by generate_implied_equalities_for_column(), and generate_join_implied_equalities_normal().

eclass_useful_for_merging()

bool eclass_useful_for_merging	(	PlannerInfo *	root,
		EquivalenceClass *	eclass,
		RelOptInfo *	rel
	)

Definition at line 3223 of file equivclass.c.

{
    Relids      relids;
    ListCell   *lc;
 
    Assert(!eclass->ec_merged);
 
    /*
     * Won't generate joinclauses if const or single-member (the latter test
     * covers the volatile case too)
     */
    if (eclass->ec_has_const || list_length(eclass->ec_members) <= 1)
        return false;
 
    /*
     * Note we don't test ec_broken; if we did, we'd need a separate code path
     * to look through ec_sources.  Checking the members anyway is OK as a
     * possibly-overoptimistic heuristic.
     */
 
    /* If specified rel is a child, we must consider the topmost parent rel */
    if (IS_OTHER_REL(rel))
    {
        Assert(!bms_is_empty(rel->top_parent_relids));
        relids = rel->top_parent_relids;
    }
    else
        relids = rel->relids;
 
    /* If rel already includes all members of eclass, no point in searching */
    if (bms_is_subset(eclass->ec_relids, relids))
        return false;
 
    /* To join, we need a member not in the given rel */
    foreach(lc, eclass->ec_members)
    {
        EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
 
        if (cur_em->em_is_child)
            continue;           /* ignore children here */
 
        if (!bms_overlap(cur_em->em_relids, relids))
            return true;
    }
 
    return false;
}

References Assert, bms_is_empty, bms_is_subset(), bms_overlap(), eclass(), EquivalenceMember::em_is_child, EquivalenceMember::em_relids, IS_OTHER_REL, lfirst, list_length(), RelOptInfo::relids, and RelOptInfo::top_parent_relids.

Referenced by get_useful_ecs_for_relation(), and pathkeys_useful_for_merging().

exprs_known_equal()

bool exprs_known_equal	(	PlannerInfo *	root,
		Node *	item1,
		Node *	item2
	)

Definition at line 2465 of file equivclass.c.

{
    ListCell   *lc1;
 
    foreach(lc1, root->eq_classes)
    {
        EquivalenceClass *ec = (EquivalenceClass *) lfirst(lc1);
        bool        item1member = false;
        bool        item2member = false;
        ListCell   *lc2;
 
        /* Never match to a volatile EC */
        if (ec->ec_has_volatile)
            continue;
 
        foreach(lc2, ec->ec_members)
        {
            EquivalenceMember *em = (EquivalenceMember *) lfirst(lc2);
 
            if (em->em_is_child)
                continue;       /* ignore children here */
            if (equal(item1, em->em_expr))
                item1member = true;
            else if (equal(item2, em->em_expr))
                item2member = true;
            /* Exit as soon as equality is proven */
            if (item1member && item2member)
                return true;
        }
    }
    return false;
}

References EquivalenceClass::ec_has_volatile, EquivalenceClass::ec_members, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, equal(), lfirst, and root.

Referenced by add_unique_group_var().

find_computable_ec_member()

EquivalenceMember* find_computable_ec_member	(	PlannerInfo *	root,
		EquivalenceClass *	ec,
		List *	exprs,
		Relids	relids,
		bool	require_parallel_safe
	)

Definition at line 836 of file equivclass.c.

{
    ListCell   *lc;
 
    foreach(lc, ec->ec_members)
    {
        EquivalenceMember *em = (EquivalenceMember *) lfirst(lc);
        List       *exprvars;
        ListCell   *lc2;
 
        /*
         * We shouldn't be trying to sort by an equivalence class that
         * contains a constant, so no need to consider such cases any further.
         */
        if (em->em_is_const)
            continue;
 
        /*
         * Ignore child members unless they belong to the requested rel.
         */
        if (em->em_is_child &&
            !bms_is_subset(em->em_relids, relids))
            continue;
 
        /*
         * Match if all Vars and quasi-Vars are available in "exprs".
         */
        exprvars = pull_var_clause((Node *) em->em_expr,
                                   PVC_INCLUDE_AGGREGATES |
                                   PVC_INCLUDE_WINDOWFUNCS |
                                   PVC_INCLUDE_PLACEHOLDERS);
        foreach(lc2, exprvars)
        {
            if (!is_exprlist_member(lfirst(lc2), exprs))
                break;
        }
        list_free(exprvars);
        if (lc2)
            continue;           /* we hit a non-available Var */
 
        /*
         * If requested, reject expressions that are not parallel-safe.  We
         * check this last because it's a rather expensive test.
         */
        if (require_parallel_safe &&
            !is_parallel_safe(root, (Node *) em->em_expr))
            continue;
 
        return em;              /* found usable expression */
    }
 
    return NULL;
}

References bms_is_subset(), EquivalenceClass::ec_members, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_is_const, EquivalenceMember::em_relids, is_exprlist_member(), is_parallel_safe(), lfirst, list_free(), pull_var_clause(), PVC_INCLUDE_AGGREGATES, PVC_INCLUDE_PLACEHOLDERS, PVC_INCLUDE_WINDOWFUNCS, and root.

Referenced by prepare_sort_from_pathkeys(), and relation_can_be_sorted_early().

find_derived_clause_for_ec_member()

RestrictInfo* find_derived_clause_for_ec_member	(	EquivalenceClass *	ec,
		EquivalenceMember *	em
	)

Definition at line 2607 of file equivclass.c.

{
    ListCell   *lc;
 
    Assert(ec->ec_has_const);
    Assert(!em->em_is_const);
    foreach(lc, ec->ec_derives)
    {
        RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
 
        /*
         * generate_base_implied_equalities_const will have put non-const
         * members on the left side of derived clauses.
         */
        if (rinfo->left_em == em)
            return rinfo;
    }
    return NULL;
}

References Assert, EquivalenceClass::ec_derives, EquivalenceClass::ec_has_const, EquivalenceMember::em_is_const, and lfirst.

Referenced by get_foreign_key_join_selectivity().

find_ec_member_matching_expr()

EquivalenceMember* find_ec_member_matching_expr	(	EquivalenceClass *	ec,
		Expr *	expr,
		Relids	relids
	)

Definition at line 771 of file equivclass.c.

{
    ListCell   *lc;
 
    /* We ignore binary-compatible relabeling on both ends */
    while (expr && IsA(expr, RelabelType))
        expr = ((RelabelType *) expr)->arg;
 
    foreach(lc, ec->ec_members)
    {
        EquivalenceMember *em = (EquivalenceMember *) lfirst(lc);
        Expr       *emexpr;
 
        /*
         * We shouldn't be trying to sort by an equivalence class that
         * contains a constant, so no need to consider such cases any further.
         */
        if (em->em_is_const)
            continue;
 
        /*
         * Ignore child members unless they belong to the requested rel.
         */
        if (em->em_is_child &&
            !bms_is_subset(em->em_relids, relids))
            continue;
 
        /*
         * Match if same expression (after stripping relabel).
         */
        emexpr = em->em_expr;
        while (emexpr && IsA(emexpr, RelabelType))
            emexpr = ((RelabelType *) emexpr)->arg;
 
        if (equal(emexpr, expr))
            return em;
    }
 
    return NULL;
}

References arg, bms_is_subset(), EquivalenceClass::ec_members, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_is_const, EquivalenceMember::em_relids, equal(), IsA, and lfirst.

Referenced by make_unique_from_pathkeys(), prepare_sort_from_pathkeys(), and relation_can_be_sorted_early().

find_join_domain()

static JoinDomain * find_join_domain ( PlannerInfo *  root, Relids  relids  )

static

Definition at line 2436 of file equivclass.c.

{
    ListCell   *lc;
 
    foreach(lc, root->join_domains)
    {
        JoinDomain *jdomain = (JoinDomain *) lfirst(lc);
 
        if (bms_is_subset(jdomain->jd_relids, relids))
            return jdomain;
    }
    elog(ERROR, "failed to find appropriate JoinDomain");
    return NULL;                /* keep compiler quiet */
}

References bms_is_subset(), elog, ERROR, JoinDomain::jd_relids, lfirst, and root.

Referenced by reconsider_full_join_clause(), and reconsider_outer_join_clause().

generate_base_implied_equalities()

void generate_base_implied_equalities

(

PlannerInfo *

root

)

Definition at line 1044 of file equivclass.c.

{
    int         ec_index;
    ListCell   *lc;
 
    /*
     * At this point, we're done absorbing knowledge of equivalences in the
     * query, so no further EC merging should happen, and ECs remaining in the
     * eq_classes list can be considered canonical.  (But note that it's still
     * possible for new single-member ECs to be added through
     * get_eclass_for_sort_expr().)
     */
    root->ec_merging_done = true;
 
    ec_index = 0;
    foreach(lc, root->eq_classes)
    {
        EquivalenceClass *ec = (EquivalenceClass *) lfirst(lc);
        bool        can_generate_joinclause = false;
        int         i;
 
        Assert(ec->ec_merged == NULL);  /* else shouldn't be in list */
        Assert(!ec->ec_broken); /* not yet anyway... */
 
        /*
         * Generate implied equalities that are restriction clauses.
         * Single-member ECs won't generate any deductions, either here or at
         * the join level.
         */
        if (list_length(ec->ec_members) > 1)
        {
            if (ec->ec_has_const)
                generate_base_implied_equalities_const(root, ec);
            else
                generate_base_implied_equalities_no_const(root, ec);
 
            /* Recover if we failed to generate required derived clauses */
            if (ec->ec_broken)
                generate_base_implied_equalities_broken(root, ec);
 
            /* Detect whether this EC might generate join clauses */
            can_generate_joinclause =
                (bms_membership(ec->ec_relids) == BMS_MULTIPLE);
        }
 
        /*
         * Mark the base rels cited in each eclass (which should all exist by
         * now) with the eq_classes indexes of all eclasses mentioning them.
         * This will let us avoid searching in subsequent lookups.  While
         * we're at it, we can mark base rels that have pending eclass joins;
         * this is a cheap version of has_relevant_eclass_joinclause().
         */
        i = -1;
        while ((i = bms_next_member(ec->ec_relids, i)) > 0)
        {
            RelOptInfo *rel = root->simple_rel_array[i];
 
            if (rel == NULL)    /* must be an outer join */
            {
                Assert(bms_is_member(i, root->outer_join_rels));
                continue;
            }
 
            Assert(rel->reloptkind == RELOPT_BASEREL);
 
            rel->eclass_indexes = bms_add_member(rel->eclass_indexes,
                                                 ec_index);
 
            if (can_generate_joinclause)
                rel->has_eclass_joins = true;
        }
 
        ec_index++;
    }
}

References Assert, bms_add_member(), bms_is_member(), bms_membership(), BMS_MULTIPLE, bms_next_member(), EquivalenceClass::ec_broken, EquivalenceClass::ec_has_const, EquivalenceClass::ec_members, EquivalenceClass::ec_merged, EquivalenceClass::ec_relids, RelOptInfo::eclass_indexes, generate_base_implied_equalities_broken(), generate_base_implied_equalities_const(), generate_base_implied_equalities_no_const(), RelOptInfo::has_eclass_joins, i, lfirst, list_length(), RELOPT_BASEREL, RelOptInfo::reloptkind, and root.

Referenced by query_planner().

generate_base_implied_equalities_broken()

static void generate_base_implied_equalities_broken ( PlannerInfo *  root, EquivalenceClass *  ec  )

static

Definition at line 1329 of file equivclass.c.

{
    ListCell   *lc;
 
    foreach(lc, ec->ec_sources)
    {
        RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(lc);
 
        if (ec->ec_has_const ||
            bms_membership(restrictinfo->required_relids) != BMS_MULTIPLE)
            distribute_restrictinfo_to_rels(root, restrictinfo);
    }
}

References bms_membership(), BMS_MULTIPLE, distribute_restrictinfo_to_rels(), EquivalenceClass::ec_has_const, EquivalenceClass::ec_sources, lfirst, RestrictInfo::required_relids, and root.

Referenced by generate_base_implied_equalities().

generate_base_implied_equalities_const()

static void generate_base_implied_equalities_const ( PlannerInfo *  root, EquivalenceClass *  ec  )

static

Definition at line 1124 of file equivclass.c.

{
    EquivalenceMember *const_em = NULL;
    ListCell   *lc;
 
    /*
     * In the trivial case where we just had one "var = const" clause, push
     * the original clause back into the main planner machinery.  There is
     * nothing to be gained by doing it differently, and we save the effort to
     * re-build and re-analyze an equality clause that will be exactly
     * equivalent to the old one.
     */
    if (list_length(ec->ec_members) == 2 &&
        list_length(ec->ec_sources) == 1)
    {
        RestrictInfo *restrictinfo = (RestrictInfo *) linitial(ec->ec_sources);
 
        distribute_restrictinfo_to_rels(root, restrictinfo);
        return;
    }
 
    /*
     * Find the constant member to use.  We prefer an actual constant to
     * pseudo-constants (such as Params), because the constraint exclusion
     * machinery might be able to exclude relations on the basis of generated
     * "var = const" equalities, but "var = param" won't work for that.
     */
    foreach(lc, ec->ec_members)
    {
        EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
 
        if (cur_em->em_is_const)
        {
            const_em = cur_em;
            if (IsA(cur_em->em_expr, Const))
                break;
        }
    }
    Assert(const_em != NULL);
 
    /* Generate a derived equality against each other member */
    foreach(lc, ec->ec_members)
    {
        EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
        Oid         eq_op;
        RestrictInfo *rinfo;
 
        Assert(!cur_em->em_is_child);   /* no children yet */
        if (cur_em == const_em)
            continue;
        eq_op = select_equality_operator(ec,
                                         cur_em->em_datatype,
                                         const_em->em_datatype);
        if (!OidIsValid(eq_op))
        {
            /* failed... */
            ec->ec_broken = true;
            break;
        }
 
        /*
         * We use the constant's em_jdomain as qualscope, so that if the
         * generated clause is variable-free (i.e, both EMs are consts) it
         * will be enforced at the join domain level.
         */
        rinfo = process_implied_equality(root, eq_op, ec->ec_collation,
                                         cur_em->em_expr, const_em->em_expr,
                                         const_em->em_jdomain->jd_relids,
                                         ec->ec_min_security,
                                         cur_em->em_is_const);
 
        /*
         * If the clause didn't degenerate to a constant, fill in the correct
         * markings for a mergejoinable clause, and save it in ec_derives. (We
         * will not re-use such clauses directly, but selectivity estimation
         * may consult the list later.  Note that this use of ec_derives does
         * not overlap with its use for join clauses, since we never generate
         * join clauses from an ec_has_const eclass.)
         */
        if (rinfo && rinfo->mergeopfamilies)
        {
            /* it's not redundant, so don't set parent_ec */
            rinfo->left_ec = rinfo->right_ec = ec;
            rinfo->left_em = cur_em;
            rinfo->right_em = const_em;
            ec->ec_derives = lappend(ec->ec_derives, rinfo);
        }
    }
}

References Assert, distribute_restrictinfo_to_rels(), EquivalenceClass::ec_broken, EquivalenceClass::ec_collation, EquivalenceClass::ec_derives, EquivalenceClass::ec_members, EquivalenceClass::ec_min_security, EquivalenceClass::ec_sources, EquivalenceMember::em_datatype, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_is_const, EquivalenceMember::em_jdomain, IsA, JoinDomain::jd_relids, lappend(), lfirst, linitial, list_length(), OidIsValid, process_implied_equality(), root, and select_equality_operator().

Referenced by generate_base_implied_equalities().

generate_base_implied_equalities_no_const()

static void generate_base_implied_equalities_no_const ( PlannerInfo *  root, EquivalenceClass *  ec  )

static

Definition at line 1219 of file equivclass.c.

{
    EquivalenceMember **prev_ems;
    ListCell   *lc;
 
    /*
     * We scan the EC members once and track the last-seen member for each
     * base relation.  When we see another member of the same base relation,
     * we generate "prev_em = cur_em".  This results in the minimum number of
     * derived clauses, but it's possible that it will fail when a different
     * ordering would succeed.  XXX FIXME: use a UNION-FIND algorithm similar
     * to the way we build merged ECs.  (Use a list-of-lists for each rel.)
     */
    prev_ems = (EquivalenceMember **)
        palloc0(root->simple_rel_array_size * sizeof(EquivalenceMember *));
 
    foreach(lc, ec->ec_members)
    {
        EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
        int         relid;
 
        Assert(!cur_em->em_is_child);   /* no children yet */
        if (!bms_get_singleton_member(cur_em->em_relids, &relid))
            continue;
        Assert(relid < root->simple_rel_array_size);
 
        if (prev_ems[relid] != NULL)
        {
            EquivalenceMember *prev_em = prev_ems[relid];
            Oid         eq_op;
            RestrictInfo *rinfo;
 
            eq_op = select_equality_operator(ec,
                                             prev_em->em_datatype,
                                             cur_em->em_datatype);
            if (!OidIsValid(eq_op))
            {
                /* failed... */
                ec->ec_broken = true;
                break;
            }
 
            /*
             * The expressions aren't constants, so the passed qualscope will
             * never be used to place the generated clause.  We just need to
             * be sure it covers both expressions, which em_relids should do.
             */
            rinfo = process_implied_equality(root, eq_op, ec->ec_collation,
                                             prev_em->em_expr, cur_em->em_expr,
                                             cur_em->em_relids,
                                             ec->ec_min_security,
                                             false);
 
            /*
             * If the clause didn't degenerate to a constant, fill in the
             * correct markings for a mergejoinable clause.  We don't put it
             * in ec_derives however; we don't currently need to re-find such
             * clauses, and we don't want to clutter that list with non-join
             * clauses.
             */
            if (rinfo && rinfo->mergeopfamilies)
            {
                /* it's not redundant, so don't set parent_ec */
                rinfo->left_ec = rinfo->right_ec = ec;
                rinfo->left_em = prev_em;
                rinfo->right_em = cur_em;
            }
        }
        prev_ems[relid] = cur_em;
    }
 
    pfree(prev_ems);
 
    /*
     * We also have to make sure that all the Vars used in the member clauses
     * will be available at any join node we might try to reference them at.
     * For the moment we force all the Vars to be available at all join nodes
     * for this eclass.  Perhaps this could be improved by doing some
     * pre-analysis of which members we prefer to join, but it's no worse than
     * what happened in the pre-8.3 code.
     */
    foreach(lc, ec->ec_members)
    {
        EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
        List       *vars = pull_var_clause((Node *) cur_em->em_expr,
                                           PVC_RECURSE_AGGREGATES |
                                           PVC_RECURSE_WINDOWFUNCS |
                                           PVC_INCLUDE_PLACEHOLDERS);
 
        add_vars_to_targetlist(root, vars, ec->ec_relids);
        list_free(vars);
    }
}

References add_vars_to_targetlist(), Assert, bms_get_singleton_member(), EquivalenceClass::ec_broken, EquivalenceClass::ec_collation, EquivalenceClass::ec_members, EquivalenceClass::ec_min_security, EquivalenceClass::ec_relids, EquivalenceMember::em_datatype, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_relids, lfirst, list_free(), OidIsValid, palloc0(), pfree(), process_implied_equality(), pull_var_clause(), PVC_INCLUDE_PLACEHOLDERS, PVC_RECURSE_AGGREGATES, PVC_RECURSE_WINDOWFUNCS, root, and select_equality_operator().

Referenced by generate_base_implied_equalities().

generate_implied_equalities_for_column()

List* generate_implied_equalities_for_column	(	PlannerInfo *	root,
		RelOptInfo *	rel,
		ec_matches_callback_type	callback,
		void *	callback_arg,
		Relids	prohibited_rels
	)

Definition at line 2971 of file equivclass.c.

{
    List       *result = NIL;
    bool        is_child_rel = (rel->reloptkind == RELOPT_OTHER_MEMBER_REL);
    Relids      parent_relids;
    int         i;
 
    /* Should be OK to rely on eclass_indexes */
    Assert(root->ec_merging_done);
 
    /* Indexes are available only on base or "other" member relations. */
    Assert(IS_SIMPLE_REL(rel));
 
    /* If it's a child rel, we'll need to know what its parent(s) are */
    if (is_child_rel)
        parent_relids = find_childrel_parents(root, rel);
    else
        parent_relids = NULL;   /* not used, but keep compiler quiet */
 
    i = -1;
    while ((i = bms_next_member(rel->eclass_indexes, i)) >= 0)
    {
        EquivalenceClass *cur_ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
        EquivalenceMember *cur_em;
        ListCell   *lc2;
 
        /* Sanity check eclass_indexes only contain ECs for rel */
        Assert(is_child_rel || bms_is_subset(rel->relids, cur_ec->ec_relids));
 
        /*
         * Won't generate joinclauses if const or single-member (the latter
         * test covers the volatile case too)
         */
        if (cur_ec->ec_has_const || list_length(cur_ec->ec_members) <= 1)
            continue;
 
        /*
         * Scan members, looking for a match to the target column.  Note that
         * child EC members are considered, but only when they belong to the
         * target relation.  (Unlike regular members, the same expression
         * could be a child member of more than one EC.  Therefore, it's
         * potentially order-dependent which EC a child relation's target
         * column gets matched to.  This is annoying but it only happens in
         * corner cases, so for now we live with just reporting the first
         * match.  See also get_eclass_for_sort_expr.)
         */
        cur_em = NULL;
        foreach(lc2, cur_ec->ec_members)
        {
            cur_em = (EquivalenceMember *) lfirst(lc2);
            if (bms_equal(cur_em->em_relids, rel->relids) &&
                callback(root, rel, cur_ec, cur_em, callback_arg))
                break;
            cur_em = NULL;
        }
 
        if (!cur_em)
            continue;
 
        /*
         * Found our match.  Scan the other EC members and attempt to generate
         * joinclauses.
         */
        foreach(lc2, cur_ec->ec_members)
        {
            EquivalenceMember *other_em = (EquivalenceMember *) lfirst(lc2);
            Oid         eq_op;
            RestrictInfo *rinfo;
 
            if (other_em->em_is_child)
                continue;       /* ignore children here */
 
            /* Make sure it'll be a join to a different rel */
            if (other_em == cur_em ||
                bms_overlap(other_em->em_relids, rel->relids))
                continue;
 
            /* Forget it if caller doesn't want joins to this rel */
            if (bms_overlap(other_em->em_relids, prohibited_rels))
                continue;
 
            /*
             * Also, if this is a child rel, avoid generating a useless join
             * to its parent rel(s).
             */
            if (is_child_rel &&
                bms_overlap(parent_relids, other_em->em_relids))
                continue;
 
            eq_op = select_equality_operator(cur_ec,
                                             cur_em->em_datatype,
                                             other_em->em_datatype);
            if (!OidIsValid(eq_op))
                continue;
 
            /* set parent_ec to mark as redundant with other joinclauses */
            rinfo = create_join_clause(root, cur_ec, eq_op,
                                       cur_em, other_em,
                                       cur_ec);
 
            result = lappend(result, rinfo);
        }
 
        /*
         * If somehow we failed to create any join clauses, we might as well
         * keep scanning the ECs for another match.  But if we did make any,
         * we're done, because we don't want to return non-redundant clauses.
         */
        if (result)
            break;
    }
 
    return result;
}

References Assert, bms_equal(), bms_is_subset(), bms_next_member(), bms_overlap(), callback(), create_join_clause(), EquivalenceClass::ec_has_const, EquivalenceClass::ec_members, EquivalenceClass::ec_relids, RelOptInfo::eclass_indexes, EquivalenceMember::em_datatype, EquivalenceMember::em_is_child, EquivalenceMember::em_relids, find_childrel_parents(), i, IS_SIMPLE_REL, lappend(), lfirst, list_length(), list_nth(), NIL, OidIsValid, RelOptInfo::relids, RELOPT_OTHER_MEMBER_REL, RelOptInfo::reloptkind, root, and select_equality_operator().

Referenced by create_tidscan_paths(), match_eclass_clauses_to_index(), and postgresGetForeignPaths().

generate_join_implied_equalities()

List* generate_join_implied_equalities	(	PlannerInfo *	root,
		Relids	join_relids,
		Relids	outer_relids,
		RelOptInfo *	inner_rel,
		SpecialJoinInfo *	sjinfo
	)

Definition at line 1392 of file equivclass.c.

{
    List       *result = NIL;
    Relids      inner_relids = inner_rel->relids;
    Relids      nominal_inner_relids;
    Relids      nominal_join_relids;
    Bitmapset  *matching_ecs;
    int         i;
 
    /* If inner rel is a child, extra setup work is needed */
    if (IS_OTHER_REL(inner_rel))
    {
        Assert(!bms_is_empty(inner_rel->top_parent_relids));
 
        /* Fetch relid set for the topmost parent rel */
        nominal_inner_relids = inner_rel->top_parent_relids;
        /* ECs will be marked with the parent's relid, not the child's */
        nominal_join_relids = bms_union(outer_relids, nominal_inner_relids);
        nominal_join_relids = add_outer_joins_to_relids(root,
                                                        nominal_join_relids,
                                                        sjinfo,
                                                        NULL);
    }
    else
    {
        nominal_inner_relids = inner_relids;
        nominal_join_relids = join_relids;
    }
 
    /*
     * Examine all potentially-relevant eclasses.
     *
     * If we are considering an outer join, we must include "join" clauses
     * that mention either input rel plus the outer join's relid; these
     * represent post-join filter clauses that have to be applied at this
     * join.  We don't have infrastructure that would let us identify such
     * eclasses cheaply, so just fall back to considering all eclasses
     * mentioning anything in nominal_join_relids.
     *
     * At inner joins, we can be smarter: only consider eclasses mentioning
     * both input rels.
     */
    if (sjinfo && sjinfo->ojrelid != 0)
        matching_ecs = get_eclass_indexes_for_relids(root, nominal_join_relids);
    else
        matching_ecs = get_common_eclass_indexes(root, nominal_inner_relids,
                                                 outer_relids);
 
    i = -1;
    while ((i = bms_next_member(matching_ecs, i)) >= 0)
    {
        EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
        List       *sublist = NIL;
 
        /* ECs containing consts do not need any further enforcement */
        if (ec->ec_has_const)
            continue;
 
        /* Single-member ECs won't generate any deductions */
        if (list_length(ec->ec_members) <= 1)
            continue;
 
        /* Sanity check that this eclass overlaps the join */
        Assert(bms_overlap(ec->ec_relids, nominal_join_relids));
 
        if (!ec->ec_broken)
            sublist = generate_join_implied_equalities_normal(root,
                                                              ec,
                                                              join_relids,
                                                              outer_relids,
                                                              inner_relids);
 
        /* Recover if we failed to generate required derived clauses */
        if (ec->ec_broken)
            sublist = generate_join_implied_equalities_broken(root,
                                                              ec,
                                                              nominal_join_relids,
                                                              outer_relids,
                                                              nominal_inner_relids,
                                                              inner_rel);
 
        result = list_concat(result, sublist);
    }
 
    return result;
}

References add_outer_joins_to_relids(), Assert, bms_is_empty, bms_next_member(), bms_overlap(), bms_union(), EquivalenceClass::ec_broken, EquivalenceClass::ec_has_const, EquivalenceClass::ec_members, EquivalenceClass::ec_relids, generate_join_implied_equalities_broken(), generate_join_implied_equalities_normal(), get_common_eclass_indexes(), get_eclass_indexes_for_relids(), i, IS_OTHER_REL, list_concat(), list_length(), list_nth(), NIL, SpecialJoinInfo::ojrelid, RelOptInfo::relids, root, and RelOptInfo::top_parent_relids.

Referenced by build_joinrel_restrictlist(), check_index_predicates(), get_baserel_parampathinfo(), get_joinrel_parampathinfo(), reduce_unique_semijoins(), and remove_self_joins_one_group().

generate_join_implied_equalities_broken()

static List * generate_join_implied_equalities_broken ( PlannerInfo *  root, EquivalenceClass *  ec, Relids  nominal_join_relids, Relids  outer_relids, Relids  nominal_inner_relids, RelOptInfo *  inner_rel  )

static

Definition at line 1739 of file equivclass.c.

{
    List       *result = NIL;
    ListCell   *lc;
 
    foreach(lc, ec->ec_sources)
    {
        RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(lc);
        Relids      clause_relids = restrictinfo->required_relids;
 
        if (bms_is_subset(clause_relids, nominal_join_relids) &&
            !bms_is_subset(clause_relids, outer_relids) &&
            !bms_is_subset(clause_relids, nominal_inner_relids))
            result = lappend(result, restrictinfo);
    }
 
    /*
     * If we have to translate, just brute-force apply adjust_appendrel_attrs
     * to all the RestrictInfos at once.  This will result in returning
     * RestrictInfos that are not listed in ec_derives, but there shouldn't be
     * any duplication, and it's a sufficiently narrow corner case that we
     * shouldn't sweat too much over it anyway.
     *
     * Since inner_rel might be an indirect descendant of the baserel
     * mentioned in the ec_sources clauses, we have to be prepared to apply
     * multiple levels of Var translation.
     */
    if (IS_OTHER_REL(inner_rel) && result != NIL)
        result = (List *) adjust_appendrel_attrs_multilevel(root,
                                                            (Node *) result,
                                                            inner_rel,
                                                            inner_rel->top_parent);
 
    return result;
}

References adjust_appendrel_attrs_multilevel(), bms_is_subset(), EquivalenceClass::ec_sources, IS_OTHER_REL, lappend(), lfirst, NIL, RestrictInfo::required_relids, and root.

Referenced by generate_join_implied_equalities(), and generate_join_implied_equalities_for_ecs().

generate_join_implied_equalities_for_ecs()

List* generate_join_implied_equalities_for_ecs	(	PlannerInfo *	root,
		List *	eclasses,
		Relids	join_relids,
		Relids	outer_relids,
		RelOptInfo *	inner_rel
	)

Definition at line 1492 of file equivclass.c.

{
    List       *result = NIL;
    Relids      inner_relids = inner_rel->relids;
    Relids      nominal_inner_relids;
    Relids      nominal_join_relids;
    ListCell   *lc;
 
    /* If inner rel is a child, extra setup work is needed */
    if (IS_OTHER_REL(inner_rel))
    {
        Assert(!bms_is_empty(inner_rel->top_parent_relids));
 
        /* Fetch relid set for the topmost parent rel */
        nominal_inner_relids = inner_rel->top_parent_relids;
        /* ECs will be marked with the parent's relid, not the child's */
        nominal_join_relids = bms_union(outer_relids, nominal_inner_relids);
    }
    else
    {
        nominal_inner_relids = inner_relids;
        nominal_join_relids = join_relids;
    }
 
    foreach(lc, eclasses)
    {
        EquivalenceClass *ec = (EquivalenceClass *) lfirst(lc);
        List       *sublist = NIL;
 
        /* ECs containing consts do not need any further enforcement */
        if (ec->ec_has_const)
            continue;
 
        /* Single-member ECs won't generate any deductions */
        if (list_length(ec->ec_members) <= 1)
            continue;
 
        /* We can quickly ignore any that don't overlap the join, too */
        if (!bms_overlap(ec->ec_relids, nominal_join_relids))
            continue;
 
        if (!ec->ec_broken)
            sublist = generate_join_implied_equalities_normal(root,
                                                              ec,
                                                              join_relids,
                                                              outer_relids,
                                                              inner_relids);
 
        /* Recover if we failed to generate required derived clauses */
        if (ec->ec_broken)
            sublist = generate_join_implied_equalities_broken(root,
                                                              ec,
                                                              nominal_join_relids,
                                                              outer_relids,
                                                              nominal_inner_relids,
                                                              inner_rel);
 
        result = list_concat(result, sublist);
    }
 
    return result;
}

References Assert, bms_is_empty, bms_overlap(), bms_union(), EquivalenceClass::ec_broken, EquivalenceClass::ec_has_const, EquivalenceClass::ec_members, EquivalenceClass::ec_relids, generate_join_implied_equalities_broken(), generate_join_implied_equalities_normal(), IS_OTHER_REL, lfirst, list_concat(), list_length(), NIL, RelOptInfo::relids, root, and RelOptInfo::top_parent_relids.

Referenced by get_joinrel_parampathinfo().

generate_join_implied_equalities_normal()

static List * generate_join_implied_equalities_normal ( PlannerInfo *  root, EquivalenceClass *  ec, Relids  join_relids, Relids  outer_relids, Relids  inner_relids  )

static

Definition at line 1563 of file equivclass.c.

{
    List       *result = NIL;
    List       *new_members = NIL;
    List       *outer_members = NIL;
    List       *inner_members = NIL;
    ListCell   *lc1;
 
    /*
     * First, scan the EC to identify member values that are computable at the
     * outer rel, at the inner rel, or at this relation but not in either
     * input rel.  The outer-rel members should already be enforced equal,
     * likewise for the inner-rel members.  We'll need to create clauses to
     * enforce that any newly computable members are all equal to each other
     * as well as to at least one input member, plus enforce at least one
     * outer-rel member equal to at least one inner-rel member.
     */
    foreach(lc1, ec->ec_members)
    {
        EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc1);
 
        /*
         * We don't need to check explicitly for child EC members.  This test
         * against join_relids will cause them to be ignored except when
         * considering a child inner rel, which is what we want.
         */
        if (!bms_is_subset(cur_em->em_relids, join_relids))
            continue;           /* not computable yet, or wrong child */
 
        if (bms_is_subset(cur_em->em_relids, outer_relids))
            outer_members = lappend(outer_members, cur_em);
        else if (bms_is_subset(cur_em->em_relids, inner_relids))
            inner_members = lappend(inner_members, cur_em);
        else
            new_members = lappend(new_members, cur_em);
    }
 
    /*
     * First, select the joinclause if needed.  We can equate any one outer
     * member to any one inner member, but we have to find a datatype
     * combination for which an opfamily member operator exists.  If we have
     * choices, we prefer simple Var members (possibly with RelabelType) since
     * these are (a) cheapest to compute at runtime and (b) most likely to
     * have useful statistics. Also, prefer operators that are also
     * hashjoinable.
     */
    if (outer_members && inner_members)
    {
        EquivalenceMember *best_outer_em = NULL;
        EquivalenceMember *best_inner_em = NULL;
        Oid         best_eq_op = InvalidOid;
        int         best_score = -1;
        RestrictInfo *rinfo;
 
        foreach(lc1, outer_members)
        {
            EquivalenceMember *outer_em = (EquivalenceMember *) lfirst(lc1);
            ListCell   *lc2;
 
            foreach(lc2, inner_members)
            {
                EquivalenceMember *inner_em = (EquivalenceMember *) lfirst(lc2);
                Oid         eq_op;
                int         score;
 
                eq_op = select_equality_operator(ec,
                                                 outer_em->em_datatype,
                                                 inner_em->em_datatype);
                if (!OidIsValid(eq_op))
                    continue;
                score = 0;
                if (IsA(outer_em->em_expr, Var) ||
                    (IsA(outer_em->em_expr, RelabelType) &&
                     IsA(((RelabelType *) outer_em->em_expr)->arg, Var)))
                    score++;
                if (IsA(inner_em->em_expr, Var) ||
                    (IsA(inner_em->em_expr, RelabelType) &&
                     IsA(((RelabelType *) inner_em->em_expr)->arg, Var)))
                    score++;
                if (op_hashjoinable(eq_op,
                                    exprType((Node *) outer_em->em_expr)))
                    score++;
                if (score > best_score)
                {
                    best_outer_em = outer_em;
                    best_inner_em = inner_em;
                    best_eq_op = eq_op;
                    best_score = score;
                    if (best_score == 3)
                        break;  /* no need to look further */
                }
            }
            if (best_score == 3)
                break;          /* no need to look further */
        }
        if (best_score < 0)
        {
            /* failed... */
            ec->ec_broken = true;
            return NIL;
        }
 
        /*
         * Create clause, setting parent_ec to mark it as redundant with other
         * joinclauses
         */
        rinfo = create_join_clause(root, ec, best_eq_op,
                                   best_outer_em, best_inner_em,
                                   ec);
 
        result = lappend(result, rinfo);
    }
 
    /*
     * Now deal with building restrictions for any expressions that involve
     * Vars from both sides of the join.  We have to equate all of these to
     * each other as well as to at least one old member (if any).
     *
     * XXX as in generate_base_implied_equalities_no_const, we could be a lot
     * smarter here to avoid unnecessary failures in cross-type situations.
     * For now, use the same left-to-right method used there.
     */
    if (new_members)
    {
        List       *old_members = list_concat(outer_members, inner_members);
        EquivalenceMember *prev_em = NULL;
        RestrictInfo *rinfo;
 
        /* For now, arbitrarily take the first old_member as the one to use */
        if (old_members)
            new_members = lappend(new_members, linitial(old_members));
 
        foreach(lc1, new_members)
        {
            EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc1);
 
            if (prev_em != NULL)
            {
                Oid         eq_op;
 
                eq_op = select_equality_operator(ec,
                                                 prev_em->em_datatype,
                                                 cur_em->em_datatype);
                if (!OidIsValid(eq_op))
                {
                    /* failed... */
                    ec->ec_broken = true;
                    return NIL;
                }
                /* do NOT set parent_ec, this qual is not redundant! */
                rinfo = create_join_clause(root, ec, eq_op,
                                           prev_em, cur_em,
                                           NULL);
 
                result = lappend(result, rinfo);
            }
            prev_em = cur_em;
        }
    }
 
    return result;
}

References bms_is_subset(), create_join_clause(), EquivalenceClass::ec_broken, EquivalenceClass::ec_members, EquivalenceMember::em_datatype, EquivalenceMember::em_expr, EquivalenceMember::em_relids, exprType(), InvalidOid, IsA, lappend(), lfirst, linitial, list_concat(), NIL, OidIsValid, op_hashjoinable(), root, and select_equality_operator().

Referenced by generate_join_implied_equalities(), and generate_join_implied_equalities_for_ecs().

get_common_eclass_indexes()

static Bitmapset * get_common_eclass_indexes ( PlannerInfo *  root, Relids  relids1, Relids  relids2  )

static

Definition at line 3374 of file equivclass.c.

{
    Bitmapset  *rel1ecs;
    Bitmapset  *rel2ecs;
    int         relid;
 
    rel1ecs = get_eclass_indexes_for_relids(root, relids1);
 
    /*
     * We can get away with just using the relation's eclass_indexes directly
     * when relids2 is a singleton set.
     */
    if (bms_get_singleton_member(relids2, &relid))
        rel2ecs = root->simple_rel_array[relid]->eclass_indexes;
    else
        rel2ecs = get_eclass_indexes_for_relids(root, relids2);
 
    /* Calculate and return the common EC indexes, recycling the left input. */
    return bms_int_members(rel1ecs, rel2ecs);
}

References bms_get_singleton_member(), bms_int_members(), get_eclass_indexes_for_relids(), and root.

Referenced by generate_join_implied_equalities(), and have_relevant_eclass_joinclause().

get_eclass_for_sort_expr()

EquivalenceClass* get_eclass_for_sort_expr	(	PlannerInfo *	root,
		Expr *	expr,
		List *	opfamilies,
		Oid	opcintype,
		Oid	collation,
		Index	sortref,
		Relids	rel,
		bool	create_it
	)

Definition at line 587 of file equivclass.c.

{
    JoinDomain *jdomain;
    Relids      expr_relids;
    EquivalenceClass *newec;
    EquivalenceMember *newem;
    ListCell   *lc1;
    MemoryContext oldcontext;
 
    /*
     * Ensure the expression exposes the correct type and collation.
     */
    expr = canonicalize_ec_expression(expr, opcintype, collation);
 
    /*
     * Since SortGroupClause nodes are top-level expressions (GROUP BY, ORDER
     * BY, etc), they can be presumed to belong to the top JoinDomain.
     */
    jdomain = linitial_node(JoinDomain, root->join_domains);
 
    /*
     * Scan through the existing EquivalenceClasses for a match
     */
    foreach(lc1, root->eq_classes)
    {
        EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1);
        ListCell   *lc2;
 
        /*
         * Never match to a volatile EC, except when we are looking at another
         * reference to the same volatile SortGroupClause.
         */
        if (cur_ec->ec_has_volatile &&
            (sortref == 0 || sortref != cur_ec->ec_sortref))
            continue;
 
        if (collation != cur_ec->ec_collation)
            continue;
        if (!equal(opfamilies, cur_ec->ec_opfamilies))
            continue;
 
        foreach(lc2, cur_ec->ec_members)
        {
            EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2);
 
            /*
             * Ignore child members unless they match the request.
             */
            if (cur_em->em_is_child &&
                !bms_equal(cur_em->em_relids, rel))
                continue;
 
            /*
             * Match constants only within the same JoinDomain (see
             * optimizer/README).
             */
            if (cur_em->em_is_const && cur_em->em_jdomain != jdomain)
                continue;
 
            if (opcintype == cur_em->em_datatype &&
                equal(expr, cur_em->em_expr))
            {
                /*
                 * Match!
                 *
                 * Copy the sortref if it wasn't set yet.  That may happen if
                 * the ec was constructed from a WHERE clause, i.e. it doesn't
                 * have a target reference at all.
                 */
                if (cur_ec->ec_sortref == 0 && sortref > 0)
                    cur_ec->ec_sortref = sortref;
                return cur_ec;
            }
        }
    }
 
    /* No match; does caller want a NULL result? */
    if (!create_it)
        return NULL;
 
    /*
     * OK, build a new single-member EC
     *
     * Here, we must be sure that we construct the EC in the right context.
     */
    oldcontext = MemoryContextSwitchTo(root->planner_cxt);
 
    newec = makeNode(EquivalenceClass);
    newec->ec_opfamilies = list_copy(opfamilies);
    newec->ec_collation = collation;
    newec->ec_members = NIL;
    newec->ec_sources = NIL;
    newec->ec_derives = NIL;
    newec->ec_relids = NULL;
    newec->ec_has_const = false;
    newec->ec_has_volatile = contain_volatile_functions((Node *) expr);
    newec->ec_broken = false;
    newec->ec_sortref = sortref;
    newec->ec_min_security = UINT_MAX;
    newec->ec_max_security = 0;
    newec->ec_merged = NULL;
 
    if (newec->ec_has_volatile && sortref == 0) /* should not happen */
        elog(ERROR, "volatile EquivalenceClass has no sortref");
 
    /*
     * Get the precise set of relids appearing in the expression.
     */
    expr_relids = pull_varnos(root, (Node *) expr);
 
    newem = add_eq_member(newec, copyObject(expr), expr_relids,
                          jdomain, NULL, opcintype);
 
    /*
     * add_eq_member doesn't check for volatile functions, set-returning
     * functions, aggregates, or window functions, but such could appear in
     * sort expressions; so we have to check whether its const-marking was
     * correct.
     */
    if (newec->ec_has_const)
    {
        if (newec->ec_has_volatile ||
            expression_returns_set((Node *) expr) ||
            contain_agg_clause((Node *) expr) ||
            contain_window_function((Node *) expr))
        {
            newec->ec_has_const = false;
            newem->em_is_const = false;
        }
    }
 
    root->eq_classes = lappend(root->eq_classes, newec);
 
    /*
     * If EC merging is already complete, we have to mop up by adding the new
     * EC to the eclass_indexes of the relation(s) mentioned in it.
     */
    if (root->ec_merging_done)
    {
        int         ec_index = list_length(root->eq_classes) - 1;
        int         i = -1;
 
        while ((i = bms_next_member(newec->ec_relids, i)) > 0)
        {
            RelOptInfo *rel = root->simple_rel_array[i];
 
            if (rel == NULL)    /* must be an outer join */
            {
                Assert(bms_is_member(i, root->outer_join_rels));
                continue;
            }
 
            Assert(rel->reloptkind == RELOPT_BASEREL);
 
            rel->eclass_indexes = bms_add_member(rel->eclass_indexes,
                                                 ec_index);
        }
    }
 
    MemoryContextSwitchTo(oldcontext);
 
    return newec;
}

References add_eq_member(), Assert, bms_add_member(), bms_equal(), bms_is_member(), bms_next_member(), canonicalize_ec_expression(), contain_agg_clause(), contain_volatile_functions(), contain_window_function(), copyObject, EquivalenceClass::ec_broken, EquivalenceClass::ec_collation, EquivalenceClass::ec_derives, EquivalenceClass::ec_has_const, EquivalenceClass::ec_has_volatile, EquivalenceClass::ec_max_security, EquivalenceClass::ec_members, EquivalenceClass::ec_merged, EquivalenceClass::ec_min_security, EquivalenceClass::ec_opfamilies, EquivalenceClass::ec_relids, EquivalenceClass::ec_sortref, EquivalenceClass::ec_sources, RelOptInfo::eclass_indexes, elog, EquivalenceMember::em_datatype, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_is_const, EquivalenceMember::em_jdomain, EquivalenceMember::em_relids, equal(), ERROR, expression_returns_set(), i, lappend(), lfirst, linitial_node, list_copy(), list_length(), makeNode, MemoryContextSwitchTo(), NIL, pull_varnos(), RELOPT_BASEREL, RelOptInfo::reloptkind, and root.

Referenced by convert_subquery_pathkeys(), initialize_mergeclause_eclasses(), and make_pathkey_from_sortinfo().

get_eclass_indexes_for_relids()

static Bitmapset * get_eclass_indexes_for_relids ( PlannerInfo *  root, Relids  relids  )

static

Definition at line 3344 of file equivclass.c.

{
    Bitmapset  *ec_indexes = NULL;
    int         i = -1;
 
    /* Should be OK to rely on eclass_indexes */
    Assert(root->ec_merging_done);
 
    while ((i = bms_next_member(relids, i)) > 0)
    {
        RelOptInfo *rel = root->simple_rel_array[i];
 
        if (rel == NULL)        /* must be an outer join */
        {
            Assert(bms_is_member(i, root->outer_join_rels));
            continue;
        }
 
        ec_indexes = bms_add_members(ec_indexes, rel->eclass_indexes);
    }
    return ec_indexes;
}

References Assert, bms_add_members(), bms_is_member(), bms_next_member(), RelOptInfo::eclass_indexes, i, and root.

Referenced by add_child_join_rel_equivalences(), generate_join_implied_equalities(), get_common_eclass_indexes(), and has_relevant_eclass_joinclause().

has_relevant_eclass_joinclause()

bool has_relevant_eclass_joinclause	(	PlannerInfo *	root,
		RelOptInfo *	rel1
	)

Definition at line 3179 of file equivclass.c.

{
    Bitmapset  *matched_ecs;
    int         i;
 
    /* Examine only eclasses mentioning rel1 */
    matched_ecs = get_eclass_indexes_for_relids(root, rel1->relids);
 
    i = -1;
    while ((i = bms_next_member(matched_ecs, i)) >= 0)
    {
        EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes,
                                                             i);
 
        /*
         * Won't generate joinclauses if single-member (this test covers the
         * volatile case too)
         */
        if (list_length(ec->ec_members) <= 1)
            continue;
 
        /*
         * Per the comment in have_relevant_eclass_joinclause, it's sufficient
         * to find an EC that mentions both this rel and some other rel.
         */
        if (!bms_is_subset(ec->ec_relids, rel1->relids))
            return true;
    }
 
    return false;
}

References bms_is_subset(), bms_next_member(), EquivalenceClass::ec_members, EquivalenceClass::ec_relids, get_eclass_indexes_for_relids(), i, list_length(), list_nth(), RelOptInfo::relids, and root.

Referenced by build_join_rel().

have_relevant_eclass_joinclause()

bool have_relevant_eclass_joinclause	(	PlannerInfo *	root,
		RelOptInfo *	rel1,
		RelOptInfo *	rel2
	)

Definition at line 3103 of file equivclass.c.

{
    Bitmapset  *matching_ecs;
    int         i;
 
    /*
     * Examine only eclasses mentioning both rel1 and rel2.
     *
     * Note that we do not consider the possibility of an eclass generating
     * "join" clauses that mention just one of the rels plus an outer join
     * that could be formed from them.  Although such clauses must be
     * correctly enforced when we form the outer join, they don't seem like
     * sufficient reason to prioritize this join over other ones.  The join
     * ordering rules will force the join to be made when necessary.
     */
    matching_ecs = get_common_eclass_indexes(root, rel1->relids,
                                             rel2->relids);
 
    i = -1;
    while ((i = bms_next_member(matching_ecs, i)) >= 0)
    {
        EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes,
                                                             i);
 
        /*
         * Sanity check that get_common_eclass_indexes gave only ECs
         * containing both rels.
         */
        Assert(bms_overlap(rel1->relids, ec->ec_relids));
        Assert(bms_overlap(rel2->relids, ec->ec_relids));
 
        /*
         * Won't generate joinclauses if single-member (this test covers the
         * volatile case too)
         */
        if (list_length(ec->ec_members) <= 1)
            continue;
 
        /*
         * We do not need to examine the individual members of the EC, because
         * all that we care about is whether each rel overlaps the relids of
         * at least one member, and get_common_eclass_indexes() and the single
         * member check above are sufficient to prove that.  (As with
         * have_relevant_joinclause(), it is not necessary that the EC be able
         * to form a joinclause relating exactly the two given rels, only that
         * it be able to form a joinclause mentioning both, and this will
         * surely be true if both of them overlap ec_relids.)
         *
         * Note we don't test ec_broken; if we did, we'd need a separate code
         * path to look through ec_sources.  Checking the membership anyway is
         * OK as a possibly-overoptimistic heuristic.
         *
         * We don't test ec_has_const either, even though a const eclass won't
         * generate real join clauses.  This is because if we had "WHERE a.x =
         * b.y and a.x = 42", it is worth considering a join between a and b,
         * since the join result is likely to be small even though it'll end
         * up being an unqualified nestloop.
         */
 
        return true;
    }
 
    return false;
}

References Assert, bms_next_member(), bms_overlap(), EquivalenceClass::ec_members, EquivalenceClass::ec_relids, get_common_eclass_indexes(), i, list_length(), list_nth(), RelOptInfo::relids, and root.

Referenced by have_relevant_joinclause().

is_exprlist_member()

static bool is_exprlist_member ( Expr *  node, List *  exprs  )

static

Definition at line 902 of file equivclass.c.

{
    ListCell   *lc;
 
    foreach(lc, exprs)
    {
        Expr       *expr = (Expr *) lfirst(lc);
 
        if (expr && IsA(expr, TargetEntry))
            expr = ((TargetEntry *) expr)->expr;
 
        if (equal(node, expr))
            return true;
    }
    return false;
}

References equal(), IsA, and lfirst.

Referenced by find_computable_ec_member().

is_redundant_derived_clause()

bool is_redundant_derived_clause	(	RestrictInfo *	rinfo,
		List *	clauselist
	)

Definition at line 3281 of file equivclass.c.

{
    EquivalenceClass *parent_ec = rinfo->parent_ec;
    ListCell   *lc;
 
    /* Fail if it's not a potentially-redundant clause from some EC */
    if (parent_ec == NULL)
        return false;
 
    foreach(lc, clauselist)
    {
        RestrictInfo *otherrinfo = (RestrictInfo *) lfirst(lc);
 
        if (otherrinfo->parent_ec == parent_ec)
            return true;
    }
 
    return false;
}

References lfirst.

Referenced by create_tidscan_plan().

is_redundant_with_indexclauses()

bool is_redundant_with_indexclauses	(	RestrictInfo *	rinfo,
		List *	indexclauses
	)

Definition at line 3308 of file equivclass.c.

{
    EquivalenceClass *parent_ec = rinfo->parent_ec;
    ListCell   *lc;
 
    foreach(lc, indexclauses)
    {
        IndexClause *iclause = lfirst_node(IndexClause, lc);
        RestrictInfo *otherrinfo = iclause->rinfo;
 
        /* If indexclause is lossy, it won't enforce the condition exactly */
        if (iclause->lossy)
            continue;
 
        /* Match if it's same clause (pointer equality should be enough) */
        if (rinfo == otherrinfo)
            return true;
        /* Match if derived from same EC */
        if (parent_ec && otherrinfo->parent_ec == parent_ec)
            return true;
 
        /*
         * No need to look at the derived clauses in iclause->indexquals; they
         * couldn't match if the parent clause didn't.
         */
    }
 
    return false;
}

References lfirst_node, IndexClause::lossy, and IndexClause::rinfo.

Referenced by create_indexscan_plan(), extract_nonindex_conditions(), and has_indexed_join_quals().

match_eclasses_to_foreign_key_col()

EquivalenceClass* match_eclasses_to_foreign_key_col	(	PlannerInfo *	root,
		ForeignKeyOptInfo *	fkinfo,
		int	colno
	)

Definition at line 2516 of file equivclass.c.

{
    Index       var1varno = fkinfo->con_relid;
    AttrNumber  var1attno = fkinfo->conkey[colno];
    Index       var2varno = fkinfo->ref_relid;
    AttrNumber  var2attno = fkinfo->confkey[colno];
    Oid         eqop = fkinfo->conpfeqop[colno];
    RelOptInfo *rel1 = root->simple_rel_array[var1varno];
    RelOptInfo *rel2 = root->simple_rel_array[var2varno];
    List       *opfamilies = NIL;   /* compute only if needed */
    Bitmapset  *matching_ecs;
    int         i;
 
    /* Consider only eclasses mentioning both relations */
    Assert(root->ec_merging_done);
    Assert(IS_SIMPLE_REL(rel1));
    Assert(IS_SIMPLE_REL(rel2));
    matching_ecs = bms_intersect(rel1->eclass_indexes,
                                 rel2->eclass_indexes);
 
    i = -1;
    while ((i = bms_next_member(matching_ecs, i)) >= 0)
    {
        EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes,
                                                             i);
        EquivalenceMember *item1_em = NULL;
        EquivalenceMember *item2_em = NULL;
        ListCell   *lc2;
 
        /* Never match to a volatile EC */
        if (ec->ec_has_volatile)
            continue;
        /* Note: it seems okay to match to "broken" eclasses here */
 
        foreach(lc2, ec->ec_members)
        {
            EquivalenceMember *em = (EquivalenceMember *) lfirst(lc2);
            Var        *var;
 
            if (em->em_is_child)
                continue;       /* ignore children here */
 
            /* EM must be a Var, possibly with RelabelType */
            var = (Var *) em->em_expr;
            while (var && IsA(var, RelabelType))
                var = (Var *) ((RelabelType *) var)->arg;
            if (!(var && IsA(var, Var)))
                continue;
 
            /* Match? */
            if (var->varno == var1varno && var->varattno == var1attno)
                item1_em = em;
            else if (var->varno == var2varno && var->varattno == var2attno)
                item2_em = em;
 
            /* Have we found both PK and FK column in this EC? */
            if (item1_em && item2_em)
            {
                /*
                 * Succeed if eqop matches EC's opfamilies.  We could test
                 * this before scanning the members, but it's probably cheaper
                 * to test for member matches first.
                 */
                if (opfamilies == NIL)  /* compute if we didn't already */
                    opfamilies = get_mergejoin_opfamilies(eqop);
                if (equal(opfamilies, ec->ec_opfamilies))
                {
                    fkinfo->eclass[colno] = ec;
                    fkinfo->fk_eclass_member[colno] = item2_em;
                    return ec;
                }
                /* Otherwise, done with this EC, move on to the next */
                break;
            }
        }
    }
    return NULL;
}

References Assert, bms_intersect(), bms_next_member(), ForeignKeyOptInfo::con_relid, EquivalenceClass::ec_has_volatile, EquivalenceClass::ec_members, EquivalenceClass::ec_opfamilies, ForeignKeyOptInfo::eclass, RelOptInfo::eclass_indexes, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, equal(), ForeignKeyOptInfo::fk_eclass_member, get_mergejoin_opfamilies(), i, IS_SIMPLE_REL, IsA, lfirst, list_nth(), NIL, ForeignKeyOptInfo::ref_relid, root, Var::varattno, Var::varno, and while().

Referenced by match_foreign_keys_to_quals().

process_equivalence()

bool process_equivalence	(	PlannerInfo *	root,
		RestrictInfo **	p_restrictinfo,
		JoinDomain *	jdomain
	)

Definition at line 118 of file equivclass.c.

{
    RestrictInfo *restrictinfo = *p_restrictinfo;
    Expr       *clause = restrictinfo->clause;
    Oid         opno,
                collation,
                item1_type,
                item2_type;
    Expr       *item1;
    Expr       *item2;
    Relids      item1_relids,
                item2_relids;
    List       *opfamilies;
    EquivalenceClass *ec1,
               *ec2;
    EquivalenceMember *em1,
               *em2;
    ListCell   *lc1;
    int         ec2_idx;
 
    /* Should not already be marked as having generated an eclass */
    Assert(restrictinfo->left_ec == NULL);
    Assert(restrictinfo->right_ec == NULL);
 
    /* Reject if it is potentially postponable by security considerations */
    if (restrictinfo->security_level > 0 && !restrictinfo->leakproof)
        return false;
 
    /* Extract info from given clause */
    Assert(is_opclause(clause));
    opno = ((OpExpr *) clause)->opno;
    collation = ((OpExpr *) clause)->inputcollid;
    item1 = (Expr *) get_leftop(clause);
    item2 = (Expr *) get_rightop(clause);
    item1_relids = restrictinfo->left_relids;
    item2_relids = restrictinfo->right_relids;
 
    /*
     * Ensure both input expressions expose the desired collation (their types
     * should be OK already); see comments for canonicalize_ec_expression.
     */
    item1 = canonicalize_ec_expression(item1,
                                       exprType((Node *) item1),
                                       collation);
    item2 = canonicalize_ec_expression(item2,
                                       exprType((Node *) item2),
                                       collation);
 
    /*
     * Clauses of the form X=X cannot be translated into EquivalenceClasses.
     * We'd either end up with a single-entry EC, losing the knowledge that
     * the clause was present at all, or else make an EC with duplicate
     * entries, causing other issues.
     */
    if (equal(item1, item2))
    {
        /*
         * If the operator is strict, then the clause can be treated as just
         * "X IS NOT NULL".  (Since we know we are considering a top-level
         * qual, we can ignore the difference between FALSE and NULL results.)
         * It's worth making the conversion because we'll typically get a much
         * better selectivity estimate than we would for X=X.
         *
         * If the operator is not strict, we can't be sure what it will do
         * with NULLs, so don't attempt to optimize it.
         */
        set_opfuncid((OpExpr *) clause);
        if (func_strict(((OpExpr *) clause)->opfuncid))
        {
            NullTest   *ntest = makeNode(NullTest);
 
            ntest->arg = item1;
            ntest->nulltesttype = IS_NOT_NULL;
            ntest->argisrow = false;    /* correct even if composite arg */
            ntest->location = -1;
 
            *p_restrictinfo =
                make_restrictinfo(root,
                                  (Expr *) ntest,
                                  restrictinfo->is_pushed_down,
                                  restrictinfo->has_clone,
                                  restrictinfo->is_clone,
                                  restrictinfo->pseudoconstant,
                                  restrictinfo->security_level,
                                  NULL,
                                  restrictinfo->incompatible_relids,
                                  restrictinfo->outer_relids);
        }
        return false;
    }
 
    /*
     * We use the declared input types of the operator, not exprType() of the
     * inputs, as the nominal datatypes for opfamily lookup.  This presumes
     * that btree operators are always registered with amoplefttype and
     * amoprighttype equal to their declared input types.  We will need this
     * info anyway to build EquivalenceMember nodes, and by extracting it now
     * we can use type comparisons to short-circuit some equal() tests.
     */
    op_input_types(opno, &item1_type, &item2_type);
 
    opfamilies = restrictinfo->mergeopfamilies;
 
    /*
     * Sweep through the existing EquivalenceClasses looking for matches to
     * item1 and item2.  These are the possible outcomes:
     *
     * 1. We find both in the same EC.  The equivalence is already known, so
     * there's nothing to do.
     *
     * 2. We find both in different ECs.  Merge the two ECs together.
     *
     * 3. We find just one.  Add the other to its EC.
     *
     * 4. We find neither.  Make a new, two-entry EC.
     *
     * Note: since all ECs are built through this process or the similar
     * search in get_eclass_for_sort_expr(), it's impossible that we'd match
     * an item in more than one existing nonvolatile EC.  So it's okay to stop
     * at the first match.
     */
    ec1 = ec2 = NULL;
    em1 = em2 = NULL;
    ec2_idx = -1;
    foreach(lc1, root->eq_classes)
    {
        EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1);
        ListCell   *lc2;
 
        /* Never match to a volatile EC */
        if (cur_ec->ec_has_volatile)
            continue;
 
        /*
         * The collation has to match; check this first since it's cheaper
         * than the opfamily comparison.
         */
        if (collation != cur_ec->ec_collation)
            continue;
 
        /*
         * A "match" requires matching sets of btree opfamilies.  Use of
         * equal() for this test has implications discussed in the comments
         * for get_mergejoin_opfamilies().
         */
        if (!equal(opfamilies, cur_ec->ec_opfamilies))
            continue;
 
        foreach(lc2, cur_ec->ec_members)
        {
            EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2);
 
            Assert(!cur_em->em_is_child);   /* no children yet */
 
            /*
             * Match constants only within the same JoinDomain (see
             * optimizer/README).
             */
            if (cur_em->em_is_const && cur_em->em_jdomain != jdomain)
                continue;
 
            if (!ec1 &&
                item1_type == cur_em->em_datatype &&
                equal(item1, cur_em->em_expr))
            {
                ec1 = cur_ec;
                em1 = cur_em;
                if (ec2)
                    break;
            }
 
            if (!ec2 &&
                item2_type == cur_em->em_datatype &&
                equal(item2, cur_em->em_expr))
            {
                ec2 = cur_ec;
                ec2_idx = foreach_current_index(lc1);
                em2 = cur_em;
                if (ec1)
                    break;
            }
        }
 
        if (ec1 && ec2)
            break;
    }
 
    /* Sweep finished, what did we find? */
 
    if (ec1 && ec2)
    {
        /* If case 1, nothing to do, except add to sources */
        if (ec1 == ec2)
        {
            ec1->ec_sources = lappend(ec1->ec_sources, restrictinfo);
            ec1->ec_min_security = Min(ec1->ec_min_security,
                                       restrictinfo->security_level);
            ec1->ec_max_security = Max(ec1->ec_max_security,
                                       restrictinfo->security_level);
            /* mark the RI as associated with this eclass */
            restrictinfo->left_ec = ec1;
            restrictinfo->right_ec = ec1;
            /* mark the RI as usable with this pair of EMs */
            restrictinfo->left_em = em1;
            restrictinfo->right_em = em2;
            return true;
        }
 
        /*
         * Case 2: need to merge ec1 and ec2.  This should never happen after
         * the ECs have reached canonical state; otherwise, pathkeys could be
         * rendered non-canonical by the merge, and relation eclass indexes
         * would get broken by removal of an eq_classes list entry.
         */
        if (root->ec_merging_done)
            elog(ERROR, "too late to merge equivalence classes");
 
        /*
         * We add ec2's items to ec1, then set ec2's ec_merged link to point
         * to ec1 and remove ec2 from the eq_classes list.  We cannot simply
         * delete ec2 because that could leave dangling pointers in existing
         * PathKeys.  We leave it behind with a link so that the merged EC can
         * be found.
         */
        ec1->ec_members = list_concat(ec1->ec_members, ec2->ec_members);
        ec1->ec_sources = list_concat(ec1->ec_sources, ec2->ec_sources);
        ec1->ec_derives = list_concat(ec1->ec_derives, ec2->ec_derives);
        ec1->ec_relids = bms_join(ec1->ec_relids, ec2->ec_relids);
        ec1->ec_has_const |= ec2->ec_has_const;
        /* can't need to set has_volatile */
        ec1->ec_min_security = Min(ec1->ec_min_security,
                                   ec2->ec_min_security);
        ec1->ec_max_security = Max(ec1->ec_max_security,
                                   ec2->ec_max_security);
        ec2->ec_merged = ec1;
        root->eq_classes = list_delete_nth_cell(root->eq_classes, ec2_idx);
        /* just to avoid debugging confusion w/ dangling pointers: */
        ec2->ec_members = NIL;
        ec2->ec_sources = NIL;
        ec2->ec_derives = NIL;
        ec2->ec_relids = NULL;
        ec1->ec_sources = lappend(ec1->ec_sources, restrictinfo);
        ec1->ec_min_security = Min(ec1->ec_min_security,
                                   restrictinfo->security_level);
        ec1->ec_max_security = Max(ec1->ec_max_security,
                                   restrictinfo->security_level);
        /* mark the RI as associated with this eclass */
        restrictinfo->left_ec = ec1;
        restrictinfo->right_ec = ec1;
        /* mark the RI as usable with this pair of EMs */
        restrictinfo->left_em = em1;
        restrictinfo->right_em = em2;
    }
    else if (ec1)
    {
        /* Case 3: add item2 to ec1 */
        em2 = add_eq_member(ec1, item2, item2_relids,
                            jdomain, NULL, item2_type);
        ec1->ec_sources = lappend(ec1->ec_sources, restrictinfo);
        ec1->ec_min_security = Min(ec1->ec_min_security,
                                   restrictinfo->security_level);
        ec1->ec_max_security = Max(ec1->ec_max_security,
                                   restrictinfo->security_level);
        /* mark the RI as associated with this eclass */
        restrictinfo->left_ec = ec1;
        restrictinfo->right_ec = ec1;
        /* mark the RI as usable with this pair of EMs */
        restrictinfo->left_em = em1;
        restrictinfo->right_em = em2;
    }
    else if (ec2)
    {
        /* Case 3: add item1 to ec2 */
        em1 = add_eq_member(ec2, item1, item1_relids,
                            jdomain, NULL, item1_type);
        ec2->ec_sources = lappend(ec2->ec_sources, restrictinfo);
        ec2->ec_min_security = Min(ec2->ec_min_security,
                                   restrictinfo->security_level);
        ec2->ec_max_security = Max(ec2->ec_max_security,
                                   restrictinfo->security_level);
        /* mark the RI as associated with this eclass */
        restrictinfo->left_ec = ec2;
        restrictinfo->right_ec = ec2;
        /* mark the RI as usable with this pair of EMs */
        restrictinfo->left_em = em1;
        restrictinfo->right_em = em2;
    }
    else
    {
        /* Case 4: make a new, two-entry EC */
        EquivalenceClass *ec = makeNode(EquivalenceClass);
 
        ec->ec_opfamilies = opfamilies;
        ec->ec_collation = collation;
        ec->ec_members = NIL;
        ec->ec_sources = list_make1(restrictinfo);
        ec->ec_derives = NIL;
        ec->ec_relids = NULL;
        ec->ec_has_const = false;
        ec->ec_has_volatile = false;
        ec->ec_broken = false;
        ec->ec_sortref = 0;
        ec->ec_min_security = restrictinfo->security_level;
        ec->ec_max_security = restrictinfo->security_level;
        ec->ec_merged = NULL;
        em1 = add_eq_member(ec, item1, item1_relids,
                            jdomain, NULL, item1_type);
        em2 = add_eq_member(ec, item2, item2_relids,
                            jdomain, NULL, item2_type);
 
        root->eq_classes = lappend(root->eq_classes, ec);
 
        /* mark the RI as associated with this eclass */
        restrictinfo->left_ec = ec;
        restrictinfo->right_ec = ec;
        /* mark the RI as usable with this pair of EMs */
        restrictinfo->left_em = em1;
        restrictinfo->right_em = em2;
    }
 
    return true;
}

References add_eq_member(), NullTest::arg, Assert, bms_join(), canonicalize_ec_expression(), RestrictInfo::clause, EquivalenceClass::ec_broken, EquivalenceClass::ec_collation, EquivalenceClass::ec_derives, EquivalenceClass::ec_has_const, EquivalenceClass::ec_has_volatile, EquivalenceClass::ec_max_security, EquivalenceClass::ec_members, EquivalenceClass::ec_merged, EquivalenceClass::ec_min_security, EquivalenceClass::ec_opfamilies, EquivalenceClass::ec_relids, EquivalenceClass::ec_sortref, EquivalenceClass::ec_sources, elog, EquivalenceMember::em_datatype, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_is_const, EquivalenceMember::em_jdomain, equal(), ERROR, exprType(), foreach_current_index, func_strict(), get_leftop(), get_rightop(), RestrictInfo::has_clone, RestrictInfo::incompatible_relids, RestrictInfo::is_clone, IS_NOT_NULL, is_opclause(), RestrictInfo::is_pushed_down, lappend(), lfirst, list_concat(), list_delete_nth_cell(), list_make1, NullTest::location, make_restrictinfo(), makeNode, Max, Min, NIL, NullTest::nulltesttype, op_input_types(), RestrictInfo::outer_relids, root, RestrictInfo::security_level, and set_opfuncid().

Referenced by distribute_qual_to_rels(), reconsider_full_join_clause(), and reconsider_outer_join_clause().

reconsider_full_join_clause()

static bool reconsider_full_join_clause ( PlannerInfo *  root, OuterJoinClauseInfo *  ojcinfo  )

static

Definition at line 2253 of file equivclass.c.

{
    RestrictInfo *rinfo = ojcinfo->rinfo;
    SpecialJoinInfo *sjinfo = ojcinfo->sjinfo;
    Relids      fjrelids = bms_make_singleton(sjinfo->ojrelid);
    Expr       *leftvar;
    Expr       *rightvar;
    Oid         opno,
                collation,
                left_type,
                right_type;
    Relids      left_relids,
                right_relids;
    ListCell   *lc1;
 
    /* Extract needed info from the clause */
    Assert(is_opclause(rinfo->clause));
    opno = ((OpExpr *) rinfo->clause)->opno;
    collation = ((OpExpr *) rinfo->clause)->inputcollid;
    op_input_types(opno, &left_type, &right_type);
    leftvar = (Expr *) get_leftop(rinfo->clause);
    rightvar = (Expr *) get_rightop(rinfo->clause);
    left_relids = rinfo->left_relids;
    right_relids = rinfo->right_relids;
 
    foreach(lc1, root->eq_classes)
    {
        EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1);
        EquivalenceMember *coal_em = NULL;
        bool        match;
        bool        matchleft;
        bool        matchright;
        ListCell   *lc2;
        int         coal_idx = -1;
 
        /* Ignore EC unless it contains pseudoconstants */
        if (!cur_ec->ec_has_const)
            continue;
        /* Never match to a volatile EC */
        if (cur_ec->ec_has_volatile)
            continue;
        /* It has to match the outer-join clause as to semantics, too */
        if (collation != cur_ec->ec_collation)
            continue;
        if (!equal(rinfo->mergeopfamilies, cur_ec->ec_opfamilies))
            continue;
 
        /*
         * Does it contain a COALESCE(leftvar, rightvar) construct?
         *
         * We can assume the COALESCE() inputs are in the same order as the
         * join clause, since both were automatically generated in the cases
         * we care about.
         *
         * XXX currently this may fail to match in cross-type cases because
         * the COALESCE will contain typecast operations while the join clause
         * may not (if there is a cross-type mergejoin operator available for
         * the two column types). Is it OK to strip implicit coercions from
         * the COALESCE arguments?
         */
        match = false;
        foreach(lc2, cur_ec->ec_members)
        {
            coal_em = (EquivalenceMember *) lfirst(lc2);
            Assert(!coal_em->em_is_child);  /* no children yet */
            if (IsA(coal_em->em_expr, CoalesceExpr))
            {
                CoalesceExpr *cexpr = (CoalesceExpr *) coal_em->em_expr;
                Node       *cfirst;
                Node       *csecond;
 
                if (list_length(cexpr->args) != 2)
                    continue;
                cfirst = (Node *) linitial(cexpr->args);
                csecond = (Node *) lsecond(cexpr->args);
 
                /*
                 * The COALESCE arguments will be marked as possibly nulled by
                 * the full join, while we wish to generate clauses that apply
                 * to the join's inputs.  So we must strip the join from the
                 * nullingrels fields of cfirst/csecond before comparing them
                 * to leftvar/rightvar.  (Perhaps with a less hokey
                 * representation for FULL JOIN USING output columns, this
                 * wouldn't be needed?)
                 */
                cfirst = remove_nulling_relids(cfirst, fjrelids, NULL);
                csecond = remove_nulling_relids(csecond, fjrelids, NULL);
 
                if (equal(leftvar, cfirst) && equal(rightvar, csecond))
                {
                    coal_idx = foreach_current_index(lc2);
                    match = true;
                    break;
                }
            }
        }
        if (!match)
            continue;           /* no match, so ignore this EC */
 
        /*
         * Yes it does!  Try to generate clauses LEFTVAR = CONSTANT and
         * RIGHTVAR = CONSTANT for each CONSTANT in the EC.  Note that we must
         * succeed with at least one constant for each var before we can
         * decide to throw away the outer-join clause.
         */
        matchleft = matchright = false;
        foreach(lc2, cur_ec->ec_members)
        {
            EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2);
            Oid         eq_op;
            RestrictInfo *newrinfo;
            JoinDomain *jdomain;
 
            if (!cur_em->em_is_const)
                continue;       /* ignore non-const members */
            eq_op = select_equality_operator(cur_ec,
                                             left_type,
                                             cur_em->em_datatype);
            if (OidIsValid(eq_op))
            {
                newrinfo = build_implied_join_equality(root,
                                                       eq_op,
                                                       cur_ec->ec_collation,
                                                       leftvar,
                                                       cur_em->em_expr,
                                                       bms_copy(left_relids),
                                                       cur_ec->ec_min_security);
                /* This equality holds within the lefthand child JoinDomain */
                jdomain = find_join_domain(root, sjinfo->syn_lefthand);
                if (process_equivalence(root, &newrinfo, jdomain))
                    matchleft = true;
            }
            eq_op = select_equality_operator(cur_ec,
                                             right_type,
                                             cur_em->em_datatype);
            if (OidIsValid(eq_op))
            {
                newrinfo = build_implied_join_equality(root,
                                                       eq_op,
                                                       cur_ec->ec_collation,
                                                       rightvar,
                                                       cur_em->em_expr,
                                                       bms_copy(right_relids),
                                                       cur_ec->ec_min_security);
                /* This equality holds within the righthand child JoinDomain */
                jdomain = find_join_domain(root, sjinfo->syn_righthand);
                if (process_equivalence(root, &newrinfo, jdomain))
                    matchright = true;
            }
        }
 
        /*
         * If we were able to equate both vars to constants, we're done, and
         * we can throw away the full-join clause as redundant.  Moreover, we
         * can remove the COALESCE entry from the EC, since the added
         * restrictions ensure it will always have the expected value. (We
         * don't bother trying to update ec_relids or ec_sources.)
         */
        if (matchleft && matchright)
        {
            cur_ec->ec_members = list_delete_nth_cell(cur_ec->ec_members, coal_idx);
            return true;
        }
 
        /*
         * Otherwise, fall out of the search loop, since we know the COALESCE
         * appears in at most one EC (XXX might stop being true if we allow
         * stripping of coercions above?)
         */
        break;
    }
 
    return false;               /* failed to make any deduction */
}

References CoalesceExpr::args, Assert, bms_copy(), bms_make_singleton(), build_implied_join_equality(), RestrictInfo::clause, EquivalenceClass::ec_collation, EquivalenceClass::ec_has_const, EquivalenceClass::ec_has_volatile, EquivalenceClass::ec_members, EquivalenceClass::ec_min_security, EquivalenceClass::ec_opfamilies, EquivalenceMember::em_datatype, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_is_const, equal(), find_join_domain(), foreach_current_index, get_leftop(), get_rightop(), if(), is_opclause(), IsA, lfirst, linitial, list_delete_nth_cell(), list_length(), lsecond, OidIsValid, SpecialJoinInfo::ojrelid, op_input_types(), process_equivalence(), remove_nulling_relids(), OuterJoinClauseInfo::rinfo, root, select_equality_operator(), OuterJoinClauseInfo::sjinfo, SpecialJoinInfo::syn_lefthand, and SpecialJoinInfo::syn_righthand.

Referenced by reconsider_outer_join_clauses().

reconsider_outer_join_clause()

static bool reconsider_outer_join_clause ( PlannerInfo *  root, OuterJoinClauseInfo *  ojcinfo, bool  outer_on_left  )

static

Definition at line 2130 of file equivclass.c.

{
    RestrictInfo *rinfo = ojcinfo->rinfo;
    SpecialJoinInfo *sjinfo = ojcinfo->sjinfo;
    Expr       *outervar,
               *innervar;
    Oid         opno,
                collation,
                left_type,
                right_type,
                inner_datatype;
    Relids      inner_relids;
    ListCell   *lc1;
 
    Assert(is_opclause(rinfo->clause));
    opno = ((OpExpr *) rinfo->clause)->opno;
    collation = ((OpExpr *) rinfo->clause)->inputcollid;
 
    /* Extract needed info from the clause */
    op_input_types(opno, &left_type, &right_type);
    if (outer_on_left)
    {
        outervar = (Expr *) get_leftop(rinfo->clause);
        innervar = (Expr *) get_rightop(rinfo->clause);
        inner_datatype = right_type;
        inner_relids = rinfo->right_relids;
    }
    else
    {
        outervar = (Expr *) get_rightop(rinfo->clause);
        innervar = (Expr *) get_leftop(rinfo->clause);
        inner_datatype = left_type;
        inner_relids = rinfo->left_relids;
    }
 
    /* Scan EquivalenceClasses for a match to outervar */
    foreach(lc1, root->eq_classes)
    {
        EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1);
        bool        match;
        ListCell   *lc2;
 
        /* Ignore EC unless it contains pseudoconstants */
        if (!cur_ec->ec_has_const)
            continue;
        /* Never match to a volatile EC */
        if (cur_ec->ec_has_volatile)
            continue;
        /* It has to match the outer-join clause as to semantics, too */
        if (collation != cur_ec->ec_collation)
            continue;
        if (!equal(rinfo->mergeopfamilies, cur_ec->ec_opfamilies))
            continue;
        /* Does it contain a match to outervar? */
        match = false;
        foreach(lc2, cur_ec->ec_members)
        {
            EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2);
 
            Assert(!cur_em->em_is_child);   /* no children yet */
            if (equal(outervar, cur_em->em_expr))
            {
                match = true;
                break;
            }
        }
        if (!match)
            continue;           /* no match, so ignore this EC */
 
        /*
         * Yes it does!  Try to generate a clause INNERVAR = CONSTANT for each
         * CONSTANT in the EC.  Note that we must succeed with at least one
         * constant before we can decide to throw away the outer-join clause.
         */
        match = false;
        foreach(lc2, cur_ec->ec_members)
        {
            EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc2);
            Oid         eq_op;
            RestrictInfo *newrinfo;
            JoinDomain *jdomain;
 
            if (!cur_em->em_is_const)
                continue;       /* ignore non-const members */
            eq_op = select_equality_operator(cur_ec,
                                             inner_datatype,
                                             cur_em->em_datatype);
            if (!OidIsValid(eq_op))
                continue;       /* can't generate equality */
            newrinfo = build_implied_join_equality(root,
                                                   eq_op,
                                                   cur_ec->ec_collation,
                                                   innervar,
                                                   cur_em->em_expr,
                                                   bms_copy(inner_relids),
                                                   cur_ec->ec_min_security);
            /* This equality holds within the OJ's child JoinDomain */
            jdomain = find_join_domain(root, sjinfo->syn_righthand);
            if (process_equivalence(root, &newrinfo, jdomain))
                match = true;
        }
 
        /*
         * If we were able to equate INNERVAR to any constant, report success.
         * Otherwise, fall out of the search loop, since we know the OUTERVAR
         * appears in at most one EC.
         */
        if (match)
            return true;
        else
            break;
    }
 
    return false;               /* failed to make any deduction */
}

References Assert, bms_copy(), build_implied_join_equality(), RestrictInfo::clause, EquivalenceClass::ec_collation, EquivalenceClass::ec_has_const, EquivalenceClass::ec_has_volatile, EquivalenceClass::ec_members, EquivalenceClass::ec_min_security, EquivalenceClass::ec_opfamilies, EquivalenceMember::em_datatype, EquivalenceMember::em_expr, EquivalenceMember::em_is_child, EquivalenceMember::em_is_const, equal(), find_join_domain(), get_leftop(), get_rightop(), is_opclause(), lfirst, OidIsValid, op_input_types(), process_equivalence(), OuterJoinClauseInfo::rinfo, root, select_equality_operator(), OuterJoinClauseInfo::sjinfo, and SpecialJoinInfo::syn_righthand.

Referenced by reconsider_outer_join_clauses().

reconsider_outer_join_clauses()

void reconsider_outer_join_clauses

(

PlannerInfo *

root

)

Definition at line 2008 of file equivclass.c.

{
    bool        found;
    ListCell   *cell;
 
    /* Outer loop repeats until we find no more deductions */
    do
    {
        found = false;
 
        /* Process the LEFT JOIN clauses */
        foreach(cell, root->left_join_clauses)
        {
            OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
 
            if (reconsider_outer_join_clause(root, ojcinfo, true))
            {
                RestrictInfo *rinfo = ojcinfo->rinfo;
 
                found = true;
                /* remove it from the list */
                root->left_join_clauses =
                    foreach_delete_current(root->left_join_clauses, cell);
                /* throw back a dummy replacement clause (see notes above) */
                rinfo = make_restrictinfo(root,
                                          (Expr *) makeBoolConst(true, false),
                                          rinfo->is_pushed_down,
                                          rinfo->has_clone,
                                          rinfo->is_clone,
                                          false,    /* pseudoconstant */
                                          0,    /* security_level */
                                          rinfo->required_relids,
                                          rinfo->incompatible_relids,
                                          rinfo->outer_relids);
                distribute_restrictinfo_to_rels(root, rinfo);
            }
        }
 
        /* Process the RIGHT JOIN clauses */
        foreach(cell, root->right_join_clauses)
        {
            OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
 
            if (reconsider_outer_join_clause(root, ojcinfo, false))
            {
                RestrictInfo *rinfo = ojcinfo->rinfo;
 
                found = true;
                /* remove it from the list */
                root->right_join_clauses =
                    foreach_delete_current(root->right_join_clauses, cell);
                /* throw back a dummy replacement clause (see notes above) */
                rinfo = make_restrictinfo(root,
                                          (Expr *) makeBoolConst(true, false),
                                          rinfo->is_pushed_down,
                                          rinfo->has_clone,
                                          rinfo->is_clone,
                                          false,    /* pseudoconstant */
                                          0,    /* security_level */
                                          rinfo->required_relids,
                                          rinfo->incompatible_relids,
                                          rinfo->outer_relids);
                distribute_restrictinfo_to_rels(root, rinfo);
            }
        }
 
        /* Process the FULL JOIN clauses */
        foreach(cell, root->full_join_clauses)
        {
            OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
 
            if (reconsider_full_join_clause(root, ojcinfo))
            {
                RestrictInfo *rinfo = ojcinfo->rinfo;
 
                found = true;
                /* remove it from the list */
                root->full_join_clauses =
                    foreach_delete_current(root->full_join_clauses, cell);
                /* throw back a dummy replacement clause (see notes above) */
                rinfo = make_restrictinfo(root,
                                          (Expr *) makeBoolConst(true, false),
                                          rinfo->is_pushed_down,
                                          rinfo->has_clone,
                                          rinfo->is_clone,
                                          false,    /* pseudoconstant */
                                          0,    /* security_level */
                                          rinfo->required_relids,
                                          rinfo->incompatible_relids,
                                          rinfo->outer_relids);
                distribute_restrictinfo_to_rels(root, rinfo);
            }
        }
    } while (found);
 
    /* Now, any remaining clauses have to be thrown back */
    foreach(cell, root->left_join_clauses)
    {
        OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
 
        distribute_restrictinfo_to_rels(root, ojcinfo->rinfo);
    }
    foreach(cell, root->right_join_clauses)
    {
        OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
 
        distribute_restrictinfo_to_rels(root, ojcinfo->rinfo);
    }
    foreach(cell, root->full_join_clauses)
    {
        OuterJoinClauseInfo *ojcinfo = (OuterJoinClauseInfo *) lfirst(cell);
 
        distribute_restrictinfo_to_rels(root, ojcinfo->rinfo);
    }
}

References distribute_restrictinfo_to_rels(), foreach_delete_current, RestrictInfo::has_clone, RestrictInfo::incompatible_relids, RestrictInfo::is_clone, RestrictInfo::is_pushed_down, lfirst, make_restrictinfo(), makeBoolConst(), RestrictInfo::outer_relids, reconsider_full_join_clause(), reconsider_outer_join_clause(), RestrictInfo::required_relids, OuterJoinClauseInfo::rinfo, and root.

Referenced by query_planner().

relation_can_be_sorted_early()

bool relation_can_be_sorted_early	(	PlannerInfo *	root,
		RelOptInfo *	rel,
		EquivalenceClass *	ec,
		bool	require_parallel_safe
	)

Definition at line 933 of file equivclass.c.

{
    PathTarget *target = rel->reltarget;
    EquivalenceMember *em;
    ListCell   *lc;
 
    /*
     * Reject volatile ECs immediately; such sorts must always be postponed.
     */
    if (ec->ec_has_volatile)
        return false;
 
    /*
     * Try to find an EM directly matching some reltarget member.
     */
    foreach(lc, target->exprs)
    {
        Expr       *targetexpr = (Expr *) lfirst(lc);
 
        em = find_ec_member_matching_expr(ec, targetexpr, rel->relids);
        if (!em)
            continue;
 
        /*
         * Reject expressions involving set-returning functions, as those
         * can't be computed early either.  (Note: this test and the following
         * one are effectively checking properties of targetexpr, so there's
         * no point in asking whether some other EC member would be better.)
         */
        if (expression_returns_set((Node *) em->em_expr))
            continue;
 
        /*
         * If requested, reject expressions that are not parallel-safe.  We
         * check this last because it's a rather expensive test.
         */
        if (require_parallel_safe &&
            !is_parallel_safe(root, (Node *) em->em_expr))
            continue;
 
        return true;
    }
 
    /*
     * Try to find an expression computable from the reltarget.
     */
    em = find_computable_ec_member(root, ec, target->exprs, rel->relids,
                                   require_parallel_safe);
    if (!em)
        return false;
 
    /*
     * Reject expressions involving set-returning functions, as those can't be
     * computed early either.  (There's no point in looking for another EC
     * member in this case; since SRFs can't appear in WHERE, they cannot
     * belong to multi-member ECs.)
     */
    if (expression_returns_set((Node *) em->em_expr))
        return false;
 
    return true;
}

References EquivalenceClass::ec_has_volatile, EquivalenceMember::em_expr, expression_returns_set(), PathTarget::exprs, find_computable_ec_member(), find_ec_member_matching_expr(), is_parallel_safe(), lfirst, RelOptInfo::relids, RelOptInfo::reltarget, and root.

Referenced by get_useful_pathkeys_for_relation().

select_equality_operator()

static Oid select_equality_operator ( EquivalenceClass *  ec, Oid  lefttype, Oid  righttype  )

static

Definition at line 1788 of file equivclass.c.

{
    ListCell   *lc;
 
    foreach(lc, ec->ec_opfamilies)
    {
        Oid         opfamily = lfirst_oid(lc);
        Oid         opno;
 
        opno = get_opfamily_member(opfamily, lefttype, righttype,
                                   BTEqualStrategyNumber);
        if (!OidIsValid(opno))
            continue;
        /* If no barrier quals in query, don't worry about leaky operators */
        if (ec->ec_max_security == 0)
            return opno;
        /* Otherwise, insist that selected operators be leakproof */
        if (get_func_leakproof(get_opcode(opno)))
            return opno;
    }
    return InvalidOid;
}

References BTEqualStrategyNumber, EquivalenceClass::ec_max_security, EquivalenceClass::ec_opfamilies, get_func_leakproof(), get_opcode(), get_opfamily_member(), InvalidOid, lfirst_oid, and OidIsValid.

Referenced by generate_base_implied_equalities_const(), generate_base_implied_equalities_no_const(), generate_implied_equalities_for_column(), generate_join_implied_equalities_normal(), reconsider_full_join_clause(), and reconsider_outer_join_clause().