Prevent clobbering of utility statements in SQL function caches.

tglsfdc · tglsfdc · commit 8b47ccb624f8 · 2022-11-29T11:46:33.000-05:00
This is an oversight in commit 7c337b6: I apparently didn't think about the possibility of a SQL function being executed multiple times within a query. In that case, functions.c's primitive caching mechanism allows the same utility parse tree to be presented for execution more than once. We have to tell ProcessUtility to make a working copy of the parse tree, or bad things happen. Normally I'd add a regression test, but I think the reported crasher is dependent on some rather random implementation choices that are nowhere near functions.c, so its usefulness as a long-lived test feels questionable. In any case, this fix is clearly correct given the design choices of 7c337b6. Per bug #17702 from Xin Wen. Thanks to Daniel Gustafsson for analysis. Back-patch to v14 where the faulty commit came in (before that, the responsibility for copying scribble-able utility parse trees lay elsewhere). Discussion: https://postgr.es/m/17702-ad24fdcdd1e9047a@postgresql.org
diff --git a/src/backend/executor/functions.c b/src/backend/executor/functions.c
@@ -884,7 +884,7 @@ postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache)
 	{
 		ProcessUtility(es->qd->plannedstmt,
 					   fcache->src,
-					   false,
+					   true,	/* protect function cache's parsetree */
 					   PROCESS_UTILITY_QUERY,
 					   es->qd->params,
 					   es->qd->queryEnv,

Original file line number	Diff line number	Diff line change
`@@ -884,7 +884,7 @@ postquel_getnext(execution_state *es, SQLFunctionCachePtr fcache)`
`884`	`884`	`{`
`885`	`885`	`ProcessUtility(es->qd->plannedstmt,`
`886`	`886`	`fcache->src,`
`887`		`- false,`
	`887`	`+ true, /* protect function cache's parsetree */`
`888`	`888`	`PROCESS_UTILITY_QUERY,`
`889`	`889`	`es->qd->params,`
`890`	`890`	`es->qd->queryEnv,`