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Fix predicate-proving logic to cope with binary-compatibility cases when

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checking whether an IS NULL/IS NOT NULL clause is implied or refuted by
a strict function.  Per example from Dawid Kuroczko.
Backpatch to 8.2 since this is arguably a performance bug.
This commit is contained in:
Tom Lane 2007-07-24 17:22:07 +00:00
parent f903278e2d
commit 507b53c833
1 changed files with 36 additions and 5 deletions
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41
src/backend/optimizer/util/predtest.c
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@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/predtest.c,v 1.15 2007/05/12 19:22:35 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/predtest.c,v 1.16 2007/07/24 17:22:07 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -84,6 +84,7 @@ static bool predicate_implied_by_simple_clause(Expr *predicate, Node *clause);
static bool predicate_refuted_by_simple_clause(Expr *predicate, Node *clause);
static bool is_null_contradicts(NullTest *ntest, Node *clause);
static Node *extract_not_arg(Node *clause);
static bool list_member_strip(List *list, Expr *datum);
static bool btree_predicate_proof(Expr *predicate, Node *clause,
bool refute_it);
@ -961,11 +962,11 @@ predicate_implied_by_simple_clause(Expr *predicate, Node *clause)
if (!type_is_rowtype(exprType((Node *) nonnullarg)))
{
if (is_opclause(clause) &&
list_member(((OpExpr *) clause)->args, nonnullarg) &&
list_member_strip(((OpExpr *) clause)->args, nonnullarg) &&
op_strict(((OpExpr *) clause)->opno))
return true;
if (is_funcclause(clause) &&
list_member(((FuncExpr *) clause)->args, nonnullarg) &&
list_member_strip(((FuncExpr *) clause)->args, nonnullarg) &&
func_strict(((FuncExpr *) clause)->funcid))
return true;
}
@ -1044,11 +1045,11 @@ is_null_contradicts(NullTest *ntest, Node *clause)
/* foo IS NULL contradicts any strict op/func on foo */
if (is_opclause(clause) &&
list_member(((OpExpr *) clause)->args, isnullarg) &&
list_member_strip(((OpExpr *) clause)->args, isnullarg) &&
op_strict(((OpExpr *) clause)->opno))
return true;
if (is_funcclause(clause) &&
list_member(((FuncExpr *) clause)->args, isnullarg) &&
list_member_strip(((FuncExpr *) clause)->args, isnullarg) &&
func_strict(((FuncExpr *) clause)->funcid))
return true;
@ -1091,6 +1092,36 @@ extract_not_arg(Node *clause)
}
/*
* Check whether an Expr is equal() to any member of a list, ignoring
* any top-level RelabelType nodes. This is legitimate for the purposes
* we use it for (matching IS [NOT] NULL arguments to arguments of strict
* functions) because RelabelType doesn't change null-ness. It's helpful
* for cases such as a varchar argument of a strict function on text.
*/
static bool
list_member_strip(List *list, Expr *datum)
{
ListCell *cell;
if (datum && IsA(datum, RelabelType))
datum = ((RelabelType *) datum)->arg;
foreach(cell, list)
{
Expr *elem = (Expr *) lfirst(cell);
if (elem && IsA(elem, RelabelType))
elem = ((RelabelType *) elem)->arg;
if (equal(elem, datum))
return true;
}
return false;
}
/*
* Define an "operator implication table" for btree operators ("strategies"),
* and a similar table for refutation.