Horton

Re: Making Vars outer-join aware

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Richard Guo <guofenglinux@gmail.com>
Cc: Pg Hackers <pgsql-hackers@lists.postgresql.org>, "Finnerty, Jim" <jfinnert@amazon.com>
Date: 2022-08-24T21:18:53Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Re-allow INDEX_VAR as rt_index in ChangeVarNodes().

  2. Fix thinkos in have_unsafe_outer_join_ref; reduce to Assert check.

  3. Invent "join domains" to replace the below_outer_join hack.

  4. Do assorted mop-up in the planner.

  5. Make Vars be outer-join-aware.

  6. Invent "multibitmapsets", and use them to speed up antijoin detection.

  7. Add basic regression tests for semi/antijoin recognition.

  8. Improve performance of adjust_appendrel_attrs_multilevel.

  9. Refactor addition of PlaceHolderVars to joinrel targetlists.

  10. Use an explicit state flag to control PlaceHolderInfo creation.

  11. Make PlaceHolderInfo lookup O(1).

Richard Guo <guofenglinux@gmail.com> writes:
> On Sun, Aug 21, 2022 at 6:52 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> What I'm thinking we should do about this, once we detect that
>> this identity is applicable, is to generate *both* forms of Pbc,
>> either adding or removing the varnullingrels bits depending on
>> which form we got from the parser.

> Do you mean we generate two RestrictInfos for Pbc in the case of
> identity 3, one with varnullingrels and one without varnullingrels, and
> choose the appropriate one when forming join paths?

Right.

> Do we need to also
> generate two SpecialJoinInfos for the B/C join in the first order, with
> and without the A/B join in its min_lefthand?

No, the SpecialJoinInfos would stay as they are now.  It's already the
case that the first join's min_righthand would contain only B, and
the second one's min_righthand would contain only C.

			regards, tom lane