Fix mishandling of after-trigger state when a SQL function returns multiple

tglsfdc · tglsfdc · commit d2e17e1ddc3d · 2006-10-12T17:02:24.000Z
rows --- if the surrounding query queued any trigger events between the rows,
the events would be fired at the wrong time, leading to bizarre behavior.
Per report from Merlin Moncure.

This is a simple patch that should solve the problem fully in the back
branches, but in HEAD we also need to consider the possibility of queries
with RETURNING clauses.  Will look into a fix for that separately.
diff --git a/src/backend/executor/functions.c b/src/backend/executor/functions.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.107 2006/10/04 00:29:52 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.108 2006/10/12 17:02:24 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -327,7 +327,14 @@ postquel_start(execution_state *es, SQLFunctionCachePtr fcache)
 	/* Utility commands don't need Executor. */
 	if (es->qd->operation != CMD_UTILITY)
 	{
-		AfterTriggerBeginQuery();
+		/*
+		 * Only set up to collect queued triggers if it's not a SELECT.
+		 * This isn't just an optimization, but is necessary in case a SELECT
+		 * returns multiple rows to caller --- we mustn't exit from the
+		 * function execution with a stacked AfterTrigger level still active.
+		 */
+		if (es->qd->operation != CMD_SELECT)
+			AfterTriggerBeginQuery();
 		ExecutorStart(es->qd, 0);
 	}
 
@@ -401,7 +408,8 @@ postquel_end(execution_state *es)
 		{
 			ActiveSnapshot = es->qd->snapshot;
 
-			AfterTriggerEndQuery(es->qd->estate);
+			if (es->qd->operation != CMD_SELECT)
+				AfterTriggerEndQuery(es->qd->estate);
 			ExecutorEnd(es->qd);
 		}
 		PG_CATCH();

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/executor/functions.c,v 1.107 2006/10/04 00:29:52 momjian Exp $`
	`11`	`+ * $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.108 2006/10/12 17:02:24 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -327,7 +327,14 @@ postquel_start(execution_state *es, SQLFunctionCachePtr fcache)`
`327`	`327`	`/* Utility commands don't need Executor. */`
`328`	`328`	`if (es->qd->operation != CMD_UTILITY)`
`329`	`329`	`{`
`330`		`- AfterTriggerBeginQuery();`
	`330`	`+ /*`
	`331`	`+ * Only set up to collect queued triggers if it's not a SELECT.`
	`332`	`+ * This isn't just an optimization, but is necessary in case a SELECT`
	`333`	`+ * returns multiple rows to caller --- we mustn't exit from the`
	`334`	`+ * function execution with a stacked AfterTrigger level still active.`
	`335`	`+ */`
	`336`	`+ if (es->qd->operation != CMD_SELECT)`
	`337`	`+ AfterTriggerBeginQuery();`
`331`	`338`	`ExecutorStart(es->qd, 0);`
`332`	`339`	`}`
`333`	`340`
`@@ -401,7 +408,8 @@ postquel_end(execution_state *es)`
`401`	`408`	`{`
`402`	`409`	`ActiveSnapshot = es->qd->snapshot;`
`403`	`410`
`404`		`- AfterTriggerEndQuery(es->qd->estate);`
	`411`	`+ if (es->qd->operation != CMD_SELECT)`
	`412`	`+ AfterTriggerEndQuery(es->qd->estate);`
`405`	`413`	`ExecutorEnd(es->qd);`
`406`	`414`	`}`
`407`	`415`	`PG_CATCH();`