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

Nikolay Shaplov <dhyan@nataraj.su>

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From: Nikolay Shaplov <dhyan@nataraj.su>
To: Alena Rybakina <a.rybakina@postgrespro.ru>, Alexander Korotkov <aekorotkov@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org, Andrei Lepikhov <a.lepikhov@postgrespro.ru>, jian he <jian.universality@gmail.com>, Robert Haas <robertmhaas@gmail.com>, pgsql-hackers@postgresql.org, Peter Geoghegan <pg@bowt.ie>, "Finnerty, Jim" <jfinnert@amazon.com>, Marcos Pegoraro <marcos@f10.com.br>, teodor@sigaev.ru, Tomas Vondra <tomas.vondra@enterprisedb.com>, Peter Eisentraut <peter@eisentraut.org>, Ranier Vilela <ranier.vf@gmail.com>
Date: 2024-07-21T08:17:01Z
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,

В письме от среда, 17 июля 2024 г. 22:36:19 MSK пользователь Alexander 
Korotkov написал:

Hi All!

I am continue reading the patch, now it's newer version

First main question:

As far a I can get, the entry point for OR->ANY convertation have been moved 
to match_clause_to_indexcol funtion, that checks if some restriction can use 
index for performance.

The thing I do not understand what match_clause_to_indexcol actually received 
as arguments. Should this be set of expressions  with OR in between grouped by 
one of the expression argument?

If not I do not understand how this ever should work.

The rest is about code readability

> +	if (bms_is_member(index->rel->relid, rinfo->right_relids))
> +		return NULL;

This check it totally not obvious for person who is not deep into postgres 
code. There should go comment explaining what are we checking for, and why it 
does not suit our purposes


> +	foreach(lc, orclause->args)
> +	{
Being no great expert in postgres code, I am confused what are we iterating on 
here? Two arguments of OR statement? (a>1) OR (b>2) those in brackets? Or 
what? Comment explaining that would be a great help here.


> +if (sub_rinfo->is_pushed_down != rinfo->is_pushed_down ||
> +	sub_rinfo->is_clone != rinfo->is_clone ||
> +	sub_rinfo->security_level != rinfo->security_level ||
> +	!bms_equal(sub_rinfo->required_relids, rinfo->required_relids) ||
> +	!bms_equal(sub_rinfo->incompatible_relids, rinfo- 
incompatible_relids) ||
> +	!bms_equal(sub_rinfo->outer_relids, rinfo->outer_relids))
> +	{ 

This check it totally mind-blowing... What in the name of existence is going 
on here?

I would suggest  to split these checks into parts (compiler optimizer should 
take care about overhead)  and give each part a sane explanation.

-- 
Nikolay Shaplov aka Nataraj
Fuzzing Engineer at Postgres Professional
Matrix IM: @dhyan:nataraj.su