Possible qual postponing past ANTI-JOIN/LASJ_NOTIN-JOIN

[dh-cloud]

When optimizer is off.

For qual (NOT(EXISTS_SUBLINK) and EXPR_SUBLINK)
or qual (NOT(ANY_SUBLINK) AND EXPR_SUBLINK)

In pull_up_sublinks_qual(), after NOT(EXISTS_SUBLINK) is converted to
Anti-JOIN (or NOT(ANY_SUBLINK) => LASJ_NOTIN-JOIN), if EXPR_SUBLINK is
also successfully converted to INNER-JOIN (see convert_EXPR_to_join)
, we can encounter the scenario where qual is postponed past the anti
or lasj_notin join. It will trigger assertion failure:

Assert(j->jointype == JOIN_INNER || j->jointype == JOIN_SEMI);

FATAL: Unexpected internal error (assert.c:48)
DETAIL: FailedAssertion("!(j->jointype == JOIN_INNER || j->jointype == JOIN_SEMI)", File: "initsplan.c", Line: 1018)
server closed the connection unexpectedly
...

We can easily reproduce this issue in master and 6X branch:

CREATE TABLE A(id int, tt timestamp)
  DISTRIBUTED BY (id);

SET optimizer TO off;

-- j->jointype == JOIN_LASJ_NOTIN
SELECT
  t1.*
FROM
  A t1
WHERE
  t1.id NOT IN (SELECT id FROM A WHERE id != 4)
  AND
  t1.tt = (SELECT MIN(tt) FROM A WHERE id = t1.id);

-- j->jointype == JOIN_ANTI
SELECT
  t1.*
FROM
  A t1
WHERE
  NOT EXISTS (SELECT id FROM A WHERE id != 4 and id = t1.id)
  AND t1.tt = (SELECT MIN(tt) FROM A WHERE id = t1.id);

Add these two jointype into the Assert(). I made several simple
tests, results are ok. However, same as the code comment said, i
am also unsure if postponing quals past anti-join/lasj_notin-join
is always semantically correct.

Here are some reminders before you submit the pull request

• Add tests for the change
• Document changes
• Communicate in the mailing list if needed
• Pass make installcheck
• Review a PR in return to support the community

[kainwen]

LGTM. Thanks a lot for your contribution @dh-cloud .

I've force push to add a test case in the commit message.