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: "a.rybakina" <a.rybakina@postgrespro.ru>
Cc: pgsql-hackers@postgresql.org, Peter Geoghegan <pg@bowt.ie>, Robert Haas <robertmhaas@gmail.com>, "Finnerty, Jim" <jfinnert@amazon.com>, Marcos Pegoraro <marcos@f10.com.br>, Andrey Lepikhov <a.lepikhov@postgrespro.ru>, teodor@sigaev.ru, Ranier Vilela <ranier.vf@gmail.com>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Peter Eisentraut <peter@eisentraut.org>
Date: 2023-11-25T01:13:47Z
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,

Hi!

On Mon, Nov 13, 2023 at 9:48 PM a.rybakina <a.rybakina@postgrespro.ru> wrote:
> These days I was porting a patch for converting or expressions to ANY to
> the choose_bitmap_and function. Unfortunately, it is not possible to
> transfer the conversion there, since expressions are processed one by
> one, as far as I saw. Therefore, I tried to make the conversion earlier
> in the generate_bitmap_or_paths function, there is just a loop bypass.
> The patch turns out to be quite complicated, in my opinion, and to be
> honest, it does not work fully yet. Also, due to the fact that the index
> for the ScalarOpExpr expression is created earlier (approximately 344
> lines in the src/backend/optimizer/path/indxpath.c file), we had to call
> the generate_bitmap_or_paths function earlier. I haven't seen yet what
> problems this could potentially lead to. Patch in the attached diff file.

It seems to me there is a confusion.  I didn't mean we need to move
conversion of OR-expressions to ANY into choose_bitmap_and() function
or anything like this.  My idea was to avoid degradation of plans,
which I've seen in [1].  Current code for generation of bitmap paths
considers the possibility to split OR-expressions into distinct bitmap
index scans.  But it doesn't consider this possibility for
ANY-expressions.  So, my idea was to enhance our bitmap scan
generation to consider split values of ANY-expressions into distinct
bitmap index scans.  So, in the example [1] and similar queries
conversion of OR-expressions to ANY wouldn't affect the generation of
bitmap paths.

Links
1. https://www.postgresql.org/message-id/CAPpHfduJtO0s9E=SHUTzrCD88BH0eik0UNog1_q3XBF2wLmH6g@mail.gmail.com

------
Regards,
Alexander Korotkov