Fix failure to detect some cases of improperly-nested aggregates.

tglsfdc · tglsfdc · commit 096e708056ea · 2023-03-13T12:40:28.000-04:00
check_agg_arguments_walker() supposed that it needn't descend into the arguments of a lower-level aggregate function, but this is just wrong in the presence of multiple levels of sub-select. The oversight would lead to executor failures on queries that should be rejected. (Prior to v11, they actually were rejected, thanks to a "redundant" execution-time check.) Per bug #17835 from Anban Company. Back-patch to all supported branches. Discussion: https://postgr.es/m/17835-4f29f3098b2d0ba4@postgresql.org
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
@@ -728,8 +728,7 @@ check_agg_arguments_walker(Node *node,
 				context->min_agglevel > agglevelsup)
 				context->min_agglevel = agglevelsup;
 		}
-		/* no need to examine args of the inner aggregate */
-		return false;
+		/* Continue and descend into subtree */
 	}
 	if (IsA(node, GroupingFunc))
 	{
diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
@@ -1248,6 +1248,12 @@ select (select max(min(unique1)) from int8_tbl) from tenk1;
 ERROR:  aggregate function calls cannot be nested
 LINE 1: select (select max(min(unique1)) from int8_tbl) from tenk1;
                            ^
+select avg((select avg(a1.col1 order by (select avg(a2.col2) from tenk1 a3))
+            from tenk1 a1(col1)))
+from tenk1 a2(col2);
+ERROR:  aggregate function calls cannot be nested
+LINE 1: select avg((select avg(a1.col1 order by (select avg(a2.col2)...
+                                                        ^
 --
 -- Test removal of redundant GROUP BY columns
 --
diff --git a/src/test/regress/sql/aggregates.sql b/src/test/regress/sql/aggregates.sql
@@ -419,6 +419,9 @@ drop table minmaxtest cascade;
 -- check for correct detection of nested-aggregate errors
 select max(min(unique1)) from tenk1;
 select (select max(min(unique1)) from int8_tbl) from tenk1;
+select avg((select avg(a1.col1 order by (select avg(a2.col2) from tenk1 a3))
+            from tenk1 a1(col1)))
+from tenk1 a2(col2);
 
 --
 -- Test removal of redundant GROUP BY columns

Original file line number	Diff line number	Diff line change
`@@ -728,8 +728,7 @@ check_agg_arguments_walker(Node *node,`
`728`	`728`	`context->min_agglevel > agglevelsup)`
`729`	`729`	`context->min_agglevel = agglevelsup;`
`730`	`730`	`}`
`731`		`- /* no need to examine args of the inner aggregate */`
`732`		`- return false;`
	`731`	`+ /* Continue and descend into subtree */`
`733`	`732`	`}`
`734`	`733`	`if (IsA(node, GroupingFunc))`
`735`	`734`	`{`