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Fix crash in assign_collations_walker for EXISTS with empty SELECT list.

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We (I think I, actually) forgot about this corner case while coding
collation resolution.  Per bug #8648 from Arjen Nienhuis.
This commit is contained in:
Tom Lane
2013-12-02 20:28:45 -05:00
parent 02bb4bbc66
commit 7ab321404c
3 changed files with 24 additions and 2 deletions
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10
src/backend/parser/parse_collate.c
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@ -484,16 +484,22 @@ assign_collations_walker(Node *node, assign_collations_context *context)
* SubLink. Act as though the Query returns its first output
* column, which indeed is what it does for EXPR_SUBLINK and
* ARRAY_SUBLINK cases. In the cases where the SubLink
* returns boolean, this info will be ignored.
* returns boolean, this info will be ignored. Special case:
* in EXISTS, the Query might return no columns, in which case
* we need do nothing.
*
* We needn't recurse, since the Query is already processed.
*/
Query *qtree = (Query *) node;
TargetEntry *tent;
if (qtree->targetList == NIL)
return false;
tent = (TargetEntry *) linitial(qtree->targetList);
Assert(IsA(tent, TargetEntry));
Assert(!tent->resjunk);
if (tent->resjunk)
return false;
collation = exprCollation((Node *) tent->expr);
/* collation doesn't change if it's converted to array */
strength = COLLATE_IMPLICIT;