Horton

Re: POC, WIP: OR-clause support for indexes

Alexander Korotkov <aekorotkov@gmail.com>

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From: Alexander Korotkov <aekorotkov@gmail.com>
To: Andrei Lepikhov <lepihov@gmail.com>
Cc: Peter Geoghegan <pg@bowt.ie>, Tom Lane <tgl@sss.pgh.pa.us>, Alena Rybakina <a.rybakina@postgrespro.ru>, jian he <jian.universality@gmail.com>, Nikolay Shaplov <dhyan@nataraj.su>, pgsql-hackers@lists.postgresql.org, Robert Haas <robertmhaas@gmail.com>, pgsql-hackers@postgresql.org, Marcos Pegoraro <marcos@f10.com.br>, teodor@sigaev.ru, Peter Eisentraut <peter@eisentraut.org>, Ranier Vilela <ranier.vf@gmail.com>
Date: 2024-10-04T11:45:18Z
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. Make group_similar_or_args() reorder clause list as little as possible

  2. Allow usage of match_orclause_to_indexcol() for joins

  3. Skip not SOAP-supported indexes while transforming an OR clause into SAOP

  4. Remove the wrong assertion from match_orclause_to_indexcol()

  5. Teach bitmap path generation about transforming OR-clauses to SAOP's

  6. Transform OR-clauses to SAOP's during index matching

  7. Fix the value of or_to_any_transform_limit in postgresql.conf.sample

  8. Transform OR clauses to ANY expression

  9. MergeAttributes code deduplication

  10. SEARCH and CYCLE clauses

  11. Improve estimation of OR clauses using extended statistics.

  12. Teach btree to handle ScalarArrayOpExpr quals natively.

  13. Revise collation derivation method and expression-tree representation.

  14. Instead of trying to force WHERE clauses into CNF or DNF normal form,

On Fri, Oct 4, 2024 at 6:31 AM Andrei Lepikhov <lepihov@gmail.com> wrote:
>
> On 10/4/24 03:15, Peter Geoghegan wrote:
> > On Tue, Oct 1, 2024 at 6:25 AM Alexander Korotkov <aekorotkov@gmail.com> wrote:
> >> I think this patchset got much better, and it could possible be
> >> committed after another round of cleanup and comment/docs improvement.
> >> It would be very kind if you share your view on the decisions made in
> >> this patchset.
> Let me provide a standpoint to help Alexander.
>
> The origin reason was - to avoid multiple BitmapOr, which has some
> effects at the planning stage (memory consumption, planning time) and
> execution (execution time growth). IndexScan also works better with a
> single array (especially a hashed one) than with a long list of clauses.
> Another reason is that by spending some time identifying common operator
> family and variable-side clause equality, we open a way for future cheap
> improvements like removing duplicated constants.
> Who knows, maybe we will be capable of using this code to improve
> cardinality estimations.
>
> According to your proposal, we have had such casting to the common type
> in previous versions. Here, we avoid it intentionally: the general idea
> is about long lists of constants, and such casting causes questions
> about performance. Do I want it in the core? Yes, I do! But may we
> implement it a bit later to have time to probe the general method and
> see how it flies?


Andrei, thank you for your opinion.  Just for the record, I'm still
exploring this and will reply later today or tomorrow.

------
Regards,
Alexander Korotkov
Supabase