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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 23:08:00 +00:00
parent b410475672
commit 8685c47223
1 changed files with 11 additions and 3 deletions
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14
src/backend/parser/parse_expr.c
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@ -8,7 +8,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.185 2005/10/15 02:49:22 momjian Exp $ * $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.186 2005/11/18 23:08:00 tgl Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -1664,8 +1664,12 @@ exprTypmod(Node *expr)
int32 typmod; int32 typmod;
ListCell *arg; ListCell *arg;
if (exprType((Node *) linitial(cexpr->args)) != coalescetype)
return -1;
typmod = exprTypmod((Node *) linitial(cexpr->args)); typmod = exprTypmod((Node *) linitial(cexpr->args));
foreach(arg, cexpr->args) if (typmod < 0)
return -1; /* no point in trying harder */
for_each_cell(arg, lnext(list_head(cexpr->args)))
{ {
Node *e = (Node *) lfirst(arg); Node *e = (Node *) lfirst(arg);
@ -1688,8 +1692,12 @@ exprTypmod(Node *expr)
int32 typmod; int32 typmod;
ListCell *arg; ListCell *arg;
if (exprType((Node *) linitial(mexpr->args)) != minmaxtype)
return -1;
typmod = exprTypmod((Node *) linitial(mexpr->args)); typmod = exprTypmod((Node *) linitial(mexpr->args));
foreach(arg, mexpr->args) if (typmod < 0)
return -1; /* no point in trying harder */
for_each_cell(arg, lnext(list_head(mexpr->args)))
{ {
Node *e = (Node *) lfirst(arg); Node *e = (Node *) lfirst(arg);