Horton

Re: Making Vars outer-join aware

Ted Yu <yuzhihong@gmail.com>

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From: Ted Yu <yuzhihong@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Pg Hackers <pgsql-hackers@lists.postgresql.org>, "Finnerty, Jim" <jfinnert@amazon.com>
Date: 2022-12-23T20:59:07Z
Lists: pgsql-hackers

Commits

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  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).

On Fri, Dec 23, 2022 at 10:21 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Here's a new edition of this patch series.
>
> I shoved some preliminary refactoring into the 0001 patch,
> notably splitting deconstruct_jointree into two passes.
> 0002-0009 cover the same ground as they did before, though
> with some differences in detail.  0010-0012 are new work
> mostly aimed at removing kluges we no longer need.
>
> There are two big areas that I would still like to improve, but
> I think we've run out of time to address them in the v16 cycle:
>
> * It'd be nice to apply the regular EquivalenceClass deduction
> mechanisms to outer-join equalities, instead of the
> reconsider_outer_join_clauses kluge.  I've made several stabs at that
> without much success.  I think that the "join domain" framework added
> in 0012 is likely to provide a workable foundation, but some more
> effort is needed.
>
> * I really want to get rid of RestrictInfo.is_pushed_down and
> RINFO_IS_PUSHED_DOWN(), because those seem exceedingly awkward
> and squishy.  I've not gotten far with finding a better
> replacement there, either.
>
> Despite the work being unfinished, I feel that this has moved us a
> long way towards outer-join handling being less of a jury-rigged
> affair.
>
>                         regards, tom lane
>
> Hi,
For v8-0012-invent-join-domains.patch, in `distribute_qual_to_rels`, it
seems that `pseudoconstant` and `root->hasPseudoConstantQuals` carry the
same value.
Can the variable `pseudoconstant` be omitted ?

Cheers