Horton

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

Andrei Lepikhov <lepihov@gmail.com>

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From: Andrei Lepikhov <lepihov@gmail.com>
To: Alexander Korotkov <aekorotkov@gmail.com>, Alena Rybakina <a.rybakina@postgrespro.ru>
Cc: 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: 2025-01-13T03:39:23Z
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 1/13/25 01:39, Alexander Korotkov wrote:
> The revised patch is attached.  Most notably it revises
> group_similar_or_args() to have the same notion of const-ness as
> others.  In that function we split potential index key and constant
> early to save time on enumerating all possible index keys.  But it
> appears to be possible to split by relids bitmapsets: index key should
> use our relid, while const shouldn't.  Other that that, comments,
> commit message and naming are revised.
Hmm, I would say we should carefully review this code.
Curiously, this patch has activated the dormant problem of duplicated 
clauses in joinorclauses. Look:

EXPLAIN (COSTS OFF)
SELECT * FROM bitmap_split_or t1, bitmap_split_or t2
WHERE t1.a=t2.b OR t1.a=1;

  Nested Loop
    ->  Seq Scan on bitmap_split_or t2
    ->  Bitmap Heap Scan on bitmap_split_or t1
          Recheck Cond: (((a = t2.b) OR (a = 1)) AND
                         ((a = t2.b) OR (a = 1)))
          ->  Bitmap Index Scan on t_a_b_idx
                Index Cond: ((a = ANY (ARRAY[t2.b, 1])) AND
                             (a = ANY (ARRAY[t2.b, 1])))

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.

-- 
regards, Andrei Lepikhov