Reject SELECT ... GROUP BY GROUPING SETS (()) FOR UPDATE.

This case should be disallowed, just as FOR UPDATE with a plain
GROUP BY is disallowed; FOR UPDATE only makes sense when each row
of the query result can be identified with a single table row.
However, we missed teaching CheckSelectLocking() to check
groupingSets as well as groupClause, so that it would allow
degenerate grouping sets.  That resulted in a bad plan and
a null-pointer dereference in the executor.

Looking around for other instances of the same bug, the only one
I found was in examine_simple_variable().  That'd just lead to
silly estimates, but it should be fixed too.

Per private report from Yaoguang Chen.
Back-patch to all supported branches.

diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 201b88d1adb1d459844625c06c6182fc27eabf54..9cede29d6a816576cea0f69de15a8ee9f92fc187 100644 (file)
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -3019,7 +3019,7 @@ CheckSelectLocking(Query *qry, LockClauseStrength strength)
          translator: %s is a SQL row locking clause such as FOR UPDATE */
                 errmsg("%s is not allowed with DISTINCT clause",
                        LCS_asString(strength))));
-   if (qry->groupClause != NIL)
+   if (qry->groupClause != NIL || qry->groupingSets != NIL)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
        /*------

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 37ddda7724012687d64f846bce92520655835f16..0c8c05f6c2e8e8c21d40f1d1dafdca40d8123a9f 100644 (file)
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -5497,7 +5497,8 @@ examine_simple_variable(PlannerInfo *root, Var *var,
         * of learning something even with it.
         */
        if (subquery->setOperations ||
-           subquery->groupClause)
+           subquery->groupClause ||
+           subquery->groupingSets)
            return;
 
        /*

diff --git a/src/test/regress/expected/errors.out b/src/test/regress/expected/errors.out
index 1e7b5a70461978bc230d2a8043920ea39d64aa5d..15862d44753e07b0d59f13a56f8e4b02ab041750 100644 (file)
--- a/src/test/regress/expected/errors.out
+++ b/src/test/regress/expected/errors.out
@@ -50,6 +50,11 @@ select distinct on (foobar) * from pg_database;
 ERROR:  column "foobar" does not exist
 LINE 1: select distinct on (foobar) * from pg_database;
                             ^
+-- grouping with FOR UPDATE
+select null from pg_database group by datname for update;
+ERROR:  FOR UPDATE is not allowed with GROUP BY clause
+select null from pg_database group by grouping sets (()) for update;
+ERROR:  FOR UPDATE is not allowed with GROUP BY clause
 --
 -- DELETE
 -- missing relation name (this had better not wildcard!)

diff --git a/src/test/regress/sql/errors.sql b/src/test/regress/sql/errors.sql
index 66a56b28f62b8811dab73b5d3cb8b605b52cabb6..a7fcf72dd4509e585edef887c5ed724ee162530d 100644 (file)
--- a/src/test/regress/sql/errors.sql
+++ b/src/test/regress/sql/errors.sql
@@ -37,6 +37,10 @@ select * from pg_database where pg_database.datname = nonesuch;
 -- bad attribute name in select distinct on
 select distinct on (foobar) * from pg_database;
 
+-- grouping with FOR UPDATE
+select null from pg_database group by datname for update;
+select null from pg_database group by grouping sets (()) for update;
+
 
 --
 -- DELETE