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Teach eval_const_expressions() to simplify an ArrayCoerceExpr to a constant

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when its input is constant and the element coercion function is immutable
(or nonexistent, ie, binary-coercible case).  This is an oversight in the
8.3 implementation of ArrayCoerceExpr, and its result is that certain cases
involving IN or NOT IN with constants don't get optimized as they should be.
Per experimentation with an example from Ow Mun Heng.
This commit is contained in:
Tom Lane 2008-08-26 02:16:39 +00:00
parent bc846323d3
commit a9ff5f0722
1 changed files with 36 additions and 1 deletions
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37
src/backend/optimizer/util/clauses.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.254.2.2 2008/05/15 17:37:57 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.254.2.3 2008/08/26 02:16:39 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -2160,6 +2160,41 @@ eval_const_expressions_mutator(Node *node,
newexpr->coerceformat = expr->coerceformat;
return (Node *) newexpr;
}
if (IsA(node, ArrayCoerceExpr))
{
ArrayCoerceExpr *expr = (ArrayCoerceExpr *) node;
Expr *arg;
ArrayCoerceExpr *newexpr;
/*
* Reduce constants in the ArrayCoerceExpr's argument, then build
* a new ArrayCoerceExpr.
*/
arg = (Expr *) eval_const_expressions_mutator((Node *) expr->arg,
context);
newexpr = makeNode(ArrayCoerceExpr);
newexpr->arg = arg;
newexpr->elemfuncid = expr->elemfuncid;
newexpr->resulttype = expr->resulttype;
newexpr->resulttypmod = expr->resulttypmod;
newexpr->isExplicit = expr->isExplicit;
newexpr->coerceformat = expr->coerceformat;
/*
* If constant argument and it's a binary-coercible or immutable
* conversion, we can simplify it to a constant.
*/
if (arg && IsA(arg, Const) &&
(!OidIsValid(newexpr->elemfuncid) ||
func_volatile(newexpr->elemfuncid) == PROVOLATILE_IMMUTABLE))
return (Node *) evaluate_expr((Expr *) newexpr,
newexpr->resulttype,
newexpr->resulttypmod);
/* Else we must return the partially-simplified node */
return (Node *) newexpr;
}
if (IsA(node, CaseExpr))
{
/*----------