Commit7ab3214

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Fix crash in assign_collations_walker for EXISTS with empty SELECT list.

We (I think I, actually) forgot about this corner case while codingcollation resolution. Per bug #8648 from Arjen Nienhuis.

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Lines changed: 8 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -484,16 +484,22 @@ assign_collations_walker(Node node, assign_collations_context context)`
`484`	`484`	`* SubLink. Act as though the Query returns its first output`
`485`	`485`	`* column, which indeed is what it does for EXPR_SUBLINK and`
`486`	`486`	`* ARRAY_SUBLINK cases. In the cases where the SubLink`
`487`		`- * returns boolean, this info will be ignored.`
	`487`	`+ * returns boolean, this info will be ignored.Special case:`
	`488`	`+ * in EXISTS, the Query might return no columns, in which case`
	`489`	`+ * we need do nothing.`
`488`	`490`	`*`
`489`	`491`	`* We needn't recurse, since the Query is already processed.`
`490`	`492`	`*/`
`491`	`493`	`Queryqtree= (Query)node;`
`492`	`494`	`TargetEntry*tent;`
`493`	`495`
	`496`	`+if (qtree->targetList==NIL)`
	`497`	`+return false;`
`494`	`498`	`tent= (TargetEntry*)linitial(qtree->targetList);`
`495`	`499`	`Assert(IsA(tent,TargetEntry));`
`496`		`-Assert(!tent->resjunk);`
	`500`	`+if (tent->resjunk)`
	`501`	`+return false;`
	`502`	`+`
`497`	`503`	`collation=exprCollation((Node*)tent->expr);`
`498`	`504`	`/* collation doesn't change if it's converted to array */`
`499`	`505`	`strength=COLLATE_IMPLICIT;`

Lines changed: 10 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -700,3 +700,13 @@ explain (verbose, costs off)`
`700`	`700`	`One-Time Filter: ("VALUES".column1 = "VALUES".column1)`
`701`	`701`	`(8 rows)`
`702`	`702`
	`703`	`+--`
	`704`	`+-- Check we behave sanely in corner case of empty SELECT list (bug #8648)`
	`705`	`+--`
	`706`	`+create temp table nocolumns();`
	`707`	`+select exists(select * from nocolumns);`
	`708`	`+ exists`
	`709`	`+--------`
	`710`	`+ f`
	`711`	`+(1 row)`
	`712`	`+`

Lines changed: 6 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -405,3 +405,9 @@ explain (verbose, costs off)`
`405`	`405`	`explain (verbose, costs off)`
`406`	`406`	`select x, xfrom`
`407`	`407`	`(select (select random()where y=y)as xfrom (values(1),(2)) v(y)) ss;`
	`408`	`+`
	`409`	`+--`
	`410`	`+-- Check we behave sanely in corner case of empty SELECT list (bug #8648)`
	`411`	`+--`
	`412`	`+create temp table nocolumns();`
	`413`	`+select exists(select*from nocolumns);`

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