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Date: Wed, 21 Aug 2024 15:08:14 +0200
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Subject: Re: POC, WIP: OR-clause support for indexes
To: Alexander Korotkov <aekorotkov@gmail.com>,
 Alena Rybakina <a.rybakina@postgrespro.ru>
Cc: Nikolay Shaplov <dhyan@nataraj.su>, pgsql-hackers@lists.postgresql.org,
 jian he <jian.universality@gmail.com>, Robert Haas <robertmhaas@gmail.com>,
 pgsql-hackers@postgresql.org, Peter Geoghegan <pg@bowt.ie>,
 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>
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From: Andrei Lepikhov <a.lepikhov@postgrespro.ru>
Organization: Postgres Professional
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On 21/8/2024 02:17, Alexander Korotkov wrote:
> Also, I convert the check you've introduced in the previous message to
> op_in_opfamily(), and introduced collation check similar to
> match_opclause_to_indexcol().
Hi,
I passed through the patches with fresh sight. Conceptually, this 
approach looks much better than the previous series.
Just for the record: previously, we attempted to resolve two issues in 
one - improve the execution plan and save cycles during the 
optimisation. As I see it, it is almost impossible in this feature. So, 
I should come to terms with carrying long OR lists through the planning 
and the additional overhead this feature generates.
I also see that the optimiser has obtained additional planning 
strategies with these patches and hasn't lost any.

Couple of findings:

First:
/* Only operator clauses scan match */
Should it be:
/* Only operator clauses can match */
?
The second one:
When creating IndexClause, we assign the original and derived clauses to 
the new, containing transformed array. But logically, we should set the 
clause with a list of ORs as the original. Why did you do so?

-- 
regards,
Andrei Lepikhov
Postgres Professional