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

recursed twice on its first argument, leading to exponential time spenton a deep nest of COALESCEs ... such as a deeply nested FULL JOIN wouldproduce. Per report from Matt Carter.

1 parentb410475 commit8685c47Copy full SHA for 8685c47

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+11

-3

lines changed

src/backend/parser
- parse_expr.c

1 file changed

+11

-3

lines changed

`‎src/backend/parser/parse_expr.c`

Lines changed: 11 additions & 3 deletions

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.185 2005/10/15 02:49:22 momjian Exp $`
	`11`	`+ * $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.186 2005/11/18 23:08:00 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -1664,8 +1664,12 @@ exprTypmod(Node *expr)`
`1664`	`1664`	`int32typmod;`
`1665`	`1665`	`ListCell*arg;`
`1666`	`1666`
	`1667`	`+if (exprType((Node*)linitial(cexpr->args))!=coalescetype)`
	`1668`	`+return-1;`
`1667`	`1669`	`typmod=exprTypmod((Node*)linitial(cexpr->args));`
`1668`		`-foreach(arg,cexpr->args)`
	`1670`	`+if (typmod<0)`
	`1671`	`+return-1;/* no point in trying harder */`
	`1672`	`+for_each_cell(arg,lnext(list_head(cexpr->args)))`
`1669`	`1673`	`{`
`1670`	`1674`	`Nodee= (Node)lfirst(arg);`
`1671`	`1675`
`@@ -1688,8 +1692,12 @@ exprTypmod(Node *expr)`
`1688`	`1692`	`int32typmod;`
`1689`	`1693`	`ListCell*arg;`
`1690`	`1694`
	`1695`	`+if (exprType((Node*)linitial(mexpr->args))!=minmaxtype)`
	`1696`	`+return-1;`
`1691`	`1697`	`typmod=exprTypmod((Node*)linitial(mexpr->args));`
`1692`		`-foreach(arg,mexpr->args)`
	`1698`	`+if (typmod<0)`
	`1699`	`+return-1;/* no point in trying harder */`
	`1700`	`+for_each_cell(arg,lnext(list_head(mexpr->args)))`
`1693`	`1701`	`{`
`1694`	`1702`	`Nodee= (Node)lfirst(arg);`
`1695`	`1703`

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Commit8685c47

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`‎src/backend/parser/parse_expr.c`

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