sql: COMMENT ON broken inside SQL batches

[knz]

For context, the COMMENT ON ... is an alias for an UPSERT INTO system.comments wrapped inside an internal executor (there is no magic).

Compare the following:

1. correct behavior, for reference:

> CREATE TABLE t(x INT);
CREATE TABLE

> COMMENT ON TABLE t IS 'waa';
COMMENT ON TABLE

> COMMENT ON COLUMN t.x IS 'woo';
COMMENT ON COLUMN

> SELECT * FROM system.comments;
  type | object_id | sub_id | comment
+------+-----------+--------+---------+
     1 |        54 |      0 | waa
     2 |        54 |      1 | woo
(2 rows)

> DROP TABLE t;
DROP TABLE

2. woooops, first comment erased by second!!?!

root@127.0.0.1:25632/defaultdb> CREATE TABLE t(x INT);
CREATE TABLE

>  COMMENT ON TABLE t IS 'waa'; COMMENT ON COLUMN t.x IS 'woo';  -- two comments in one batch
COMMENT ON COLUMN

> SELECT * FROM system.comments;
  type | object_id | sub_id | comment
+------+-----------+--------+---------+
     1 |        55 |      0 | woo
     2 |        55 |      1 | woo
(2 rows)

> DROP TABLE t;
DROP TABLE

3. bigger woops, both comments missing!?!

> CREATE TABLE t(x INT);
CREATE TABLE

>  COMMENT ON TABLE t IS 'waa'; COMMENT ON COLUMN t.x IS 'woo'; SELECT * FROM system.comments; -- upsert+select in 1 batch
  type | object_id | sub_id | comment
+------+-----------+--------+---------+
     1 |        55 |      0 | .
     2 |        55 |      1 | .
(2 rows)

> DROP TABLE t;
DROP TABLE

[knz]

If I manually replace COMMENT ON by UPSERT, the behavior is fine. This points in the direction of an error in the implementation of ResolveMutableTableDescriptor or perhaps for queries routed through the internal executor.

[knz]

If I replace the call to ResolveMutableTableDescriptor by ResolveUncachedTableDescriptor, the error persists. This means the internal executor is erroneously dropping queries on the floor.