Horton

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

Pavel Borisov <pashkin.elfe@gmail.com>

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From: Pavel Borisov <pashkin.elfe@gmail.com>
To: Andrei Lepikhov <lepihov@gmail.com>
Cc: Alexander Korotkov <aekorotkov@gmail.com>, 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: 2025-01-30T13:22:55Z
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 Tue, 28 Jan 2025 at 12:42, Andrei Lepikhov <lepihov@gmail.com> wrote:
>
> On 1/28/25 11:36, Andrei Lepikhov wrote:
> > On 1/27/25 16:50, Alexander Korotkov wrote:
> > qsort(matches, n, sizeof(OrArgIndexMatch), or_arg_index_match_cmp);
> >
> > To fit an index, the order of elements in the target array of the
> > `ScalarArrayOpExpr` may change compared to the initial list of OR
> > expressions. If there are indexes that cover the same set of columns but
> > in reverse order, this could potentially alter the position of a
> > Subplan. However, I believe this is a rare case; it is supported by the
> > initial OR path and should be acceptable.
> I beg your pardon - I forgot that we've restricted the feature's scope
> and can't combine OR clauses into ScalarArrayOpExpr if the args list
> contains references to different columns.
> So, my note can't be applied here.
>
> --
> regards, Andrei Lepikhov

I've looked at the patch v46-0001
Looks good to me.

There is a test that demonstrates the behavior change. Maybe some more
cases like are also worth adding to a test.

+SELECT * FROM bitmap_split_or t1, bitmap_split_or t2 WHERE t1.a=t2.c
OR (t1.a=t2.b OR t1.a=1);
+                       QUERY PLAN
+--------------------------------------------------------
+ Nested Loop
+   ->  Seq Scan on bitmap_split_or t2
+   ->  Index Scan using t_a_b_idx on bitmap_split_or t1
+         Index Cond: (a = ANY (ARRAY[t2.c, t2.b, 1]))
+(4 rows)
+
+EXPLAIN (COSTS OFF)
+SELECT * FROM bitmap_split_or t1, bitmap_split_or t2 WHERE t1.c=t2.b OR t1.a=1;
+                  QUERY PLAN
+----------------------------------------------
+ Nested Loop
+   Join Filter: ((t1.c = t2.b) OR (t1.a = 1))
+   ->  Seq Scan on bitmap_split_or t1
+   ->  Materialize
+         ->  Seq Scan on bitmap_split_or t2
+(5 rows)
+
+EXPLAIN (COSTS OFF)

Comment
> *    Also, add any potentially usable join OR clauses to *joinorclauses
may reflect the change in v46-0001 lappend -> list_append_unique_ptr
that differs in the processing of equal clauses in the list.

Semantics mentioned in the commit message:
> 2. Make match_join_clauses_to_index() pass OR-clauses to
>        match_clause_to_index().
could also be added as comments in the section just before
match_join_clauses_to_index()

Since d4378c0005e6 comment for match_clause_to_indexcol() I think
needs change. This could be as a separate commit, not regarding
current patch v46-0001.
> * NOTE:  returns NULL if clause is an OR or AND clause; it is the
> * responsibility of higher-level routines to co

I think the patch can be pushed with possible additions to regression
test and comments.

Regards,
Pavel Borisov
Supabase