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Improve the tests to see if ScalarArrayOpExpr is strict. Original coding

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would basically punt in all cases for 'foo <> ALL (array)', which resulted
in a performance regression for NOT IN compared to what we were doing in
8.1 and before.  Per report from Pavel Stehule.
This commit is contained in:
Tom Lane 2006-02-06 22:21:12 +00:00
parent a6fefc866c
commit 72153c0582
1 changed files with 59 additions and 5 deletions
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64
src/backend/optimizer/util/clauses.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.207 2006/01/31 21:39:24 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.208 2006/02/06 22:21:12 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -70,6 +70,7 @@ static bool contain_mutable_functions_walker(Node *node, void *context);
static bool contain_volatile_functions_walker(Node *node, void *context);
static bool contain_nonstrict_functions_walker(Node *node, void *context);
static Relids find_nonnullable_rels_walker(Node *node, bool top_level);
static bool is_strict_saop(ScalarArrayOpExpr *expr, bool falseOK);
static bool set_coercionform_dontcare_walker(Node *node, void *context);
static Node *eval_const_expressions_mutator(Node *node,
eval_const_expressions_context *context);
@ -816,8 +817,11 @@ contain_nonstrict_functions_walker(Node *node, void *context)
}
if (IsA(node, ScalarArrayOpExpr))
{
/* inherently non-strict, consider null scalar and empty array */
return true;
ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
if (!is_strict_saop(expr, false))
return true;
/* else fall through to check args */
}
if (IsA(node, BoolExpr))
{
@ -937,10 +941,9 @@ find_nonnullable_rels_walker(Node *node, bool top_level)
}
else if (IsA(node, ScalarArrayOpExpr))
{
/* Strict if it's "foo op ANY array" and op is strict */
ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;
if (expr->useOr && op_strict(expr->opno))
if (is_strict_saop(expr, true))
result = find_nonnullable_rels_walker((Node *) expr->args, false);
}
else if (IsA(node, BoolExpr))
@ -991,6 +994,57 @@ find_nonnullable_rels_walker(Node *node, bool top_level)
return result;
}
/*
* Can we treat a ScalarArrayOpExpr as strict?
*
* If "falseOK" is true, then a "false" result can be considered strict,
* else we need to guarantee an actual NULL result for NULL input.
*
* "foo op ALL array" is strict if the op is strict *and* we can prove
* that the array input isn't an empty array. We can check that
* for the cases of an array constant and an ARRAY[] construct.
*
* "foo op ANY array" is strict in the falseOK sense if the op is strict.
* If not falseOK, the test is the same as for "foo op ALL array".
*/
static bool
is_strict_saop(ScalarArrayOpExpr *expr, bool falseOK)
{
Node *rightop;
/* The contained operator must be strict. */
if (!op_strict(expr->opno))
return false;
/* If ANY and falseOK, that's all we need to check. */
if (expr->useOr && falseOK)
return true;
/* Else, we have to see if the array is provably non-empty. */
Assert(list_length(expr->args) == 2);
rightop = (Node *) lsecond(expr->args);
if (rightop && IsA(rightop, Const))
{
Datum arraydatum = ((Const *) rightop)->constvalue;
bool arrayisnull = ((Const *) rightop)->constisnull;
ArrayType *arrayval;
int nitems;
if (arrayisnull)
return false;
arrayval = DatumGetArrayTypeP(arraydatum);
nitems = ArrayGetNItems(ARR_NDIM(arrayval), ARR_DIMS(arrayval));
if (nitems > 0)
return true;
}
else if (rightop && IsA(rightop, ArrayExpr))
{
ArrayExpr *arrayexpr = (ArrayExpr *) rightop;
if (arrayexpr->elements != NIL && !arrayexpr->multidims)
return true;
}
return false;
}
/*****************************************************************************
* Check for "pseudo-constant" clauses