Horton

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

Alexander Korotkov <aekorotkov@gmail.com>

View thread
From: Alexander Korotkov <aekorotkov@gmail.com>
To: Andrei Lepikhov <lepihov@gmail.com>
Cc: Alena Rybakina <a.rybakina@postgrespro.ru>, Ranier Vilela <ranier.vf@gmail.com>, Alexander Lakhin <exclusion@gmail.com>, jian he <jian.universality@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Nikolay Shaplov <dhyan@nataraj.su>, pgsql-hackers@lists.postgresql.org, pgsql-hackers@postgresql.org, Peter Geoghegan <pg@bowt.ie>, Marcos Pegoraro <marcos@f10.com.br>, teodor@sigaev.ru, Peter Eisentraut <peter@eisentraut.org>
Date: 2025-01-25T05:04:57Z
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,

Attachments

On Wed, Jan 15, 2025 at 10:24 AM Andrei Lepikhov <lepihov@gmail.com> wrote:
> On 1/13/25 10:39, Andrei Lepikhov wrote:
> > On 1/13/25 01:39, Alexander Korotkov wrote:
> > It can be resolved with a single-line change (see attached). But I need
> > some time to ponder over the changing behaviour when a clause may match
> > an index and be in joinorclauses.
> In addition, let me raise a couple of issues:
> 1. As Robert has said before, it may interfere with some short-circuit
> optimisations like below:
>
> EXPLAIN (COSTS OFF)
> SELECT * FROM bitmap_split_or t1
> WHERE t1.a=2 AND (t1.b=2 OR t1.b = (
>    SELECT sum(c1.reltuples) FROM pg_class c1, pg_class c2
>    WHERE c1.relpages=c2.relpages AND c1.relpages = t1.a));
>
> Here, a user may avoid evaluating the subplan at all if t1.b=2 all the
> time when t1.a=2. OR->ANY may accidentally shift this behaviour.
>
> 2. The query:
>
> EXPLAIN (ANALYZE, COSTS OFF)
> SELECT * FROM bitmap_split_or t1
> WHERE t1.a=2 OR t1.a = (
>    SELECT sum(c1.reltuples) FROM pg_class c1, pg_class c2
>    WHERE c1.relpages=c2.relpages AND c1.relpages = t1.a)::integer;
>
> causes SEGFAULT during index keys evaluation. I haven't dived into it
> yet, but it seems quite a typical misstep and is not difficult to fix.

Segfault appears to be caused by a typo.  Patch used parent rinfo
instead of child rinfo.  Fixed in the attached patch.

It appears that your first query also changed a plan after fixing
this.  Could you, please, provide another example of a regression for
short-circuit optimization, which is related to this patch?

Also, I've integrated your fix from [1].

Links.
1. https://www.postgresql.org/message-id/41ba3d47-2a48-476c-88d4-6ebd889a7af2%40gmail.com

------
Regards,
Alexander Korotkov
Supabase