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Fix performance issue in exprTypmod(): for a COALESCE expression, it

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recursed twice on its first argument, leading to exponential time spent
on a deep nest of COALESCEs ... such as a deeply nested FULL JOIN would
produce.  Per report from Matt Carter.
This commit is contained in:
Tom Lane 2005-11-18 23:08:43 +00:00
parent 48fabd257f
commit e03c5e2d5a
1 changed files with 6 additions and 2 deletions
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8
src/backend/parser/parse_expr.c
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@ -8,7 +8,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.163.2.3 2005/05/25 02:13:48 ishii Exp $ * $Header: /cvsroot/pgsql/src/backend/parser/parse_expr.c,v 1.163.2.4 2005/11/18 23:08:43 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -1425,8 +1425,12 @@ exprTypmod(Node *expr)
int32 typmod; int32 typmod;
List *arg; List *arg;
if (exprType((Node *) lfirst(cexpr->args)) != coalescetype)
return -1;
typmod = exprTypmod((Node *) lfirst(cexpr->args)); typmod = exprTypmod((Node *) lfirst(cexpr->args));
foreach(arg, cexpr->args) if (typmod < 0)
return -1; /* no point in trying harder */
foreach(arg, lnext(cexpr->args))
{ {
Node *e = (Node *) lfirst(arg); Node *e = (Node *) lfirst(arg);