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

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
index 4fbf80c2713c0893d1f564e24d39a503d72f4326..85cd47b7aecbbe40664d1e99624bd264adfaa22d 100644 (file)
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -736,8 +736,7 @@ 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
index e074cb71bf6b2251fc633af9d4d437f79c070981..f0517f95b603039e83b286d5ddd1e5eb322c41c1 100644 (file)
--- a/src/test/regress/expected/aggregates.out
+++ b/src/test/regress/expected/aggregates.out
@@ -1282,6 +1282,12 @@ 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
index 616ef38c25952b9c7a0a2c27f835c8a42f61b7dd..1783d19bd5e571ee537ebb2da058d383ef2e763f 100644 (file)
--- a/src/test/regress/sql/aggregates.sql
+++ b/src/test/regress/sql/aggregates.sql
@@ -439,6 +439,9 @@ 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