| From: | Andrei Lepikhov <lepihov(at)gmail(dot)com> |
|---|---|
| To: | Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
| Cc: | Alena Rybakina <a(dot)rybakina(at)postgrespro(dot)ru>, Ranier Vilela <ranier(dot)vf(at)gmail(dot)com>, Alexander Lakhin <exclusion(at)gmail(dot)com>, jian he <jian(dot)universality(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Nikolay Shaplov <dhyan(at)nataraj(dot)su>, pgsql-hackers(at)lists(dot)postgresql(dot)org, pgsql-hackers(at)postgresql(dot)org, Peter Geoghegan <pg(at)bowt(dot)ie>, Marcos Pegoraro <marcos(at)f10(dot)com(dot)br>, teodor(at)sigaev(dot)ru, Peter Eisentraut <peter(at)eisentraut(dot)org> |
| Subject: | Re: POC, WIP: OR-clause support for indexes |
| Date: | 2025-01-28 08:42:38 |
| Message-ID: | 8cf87fc0-1f79-4427-8134-9245a1a52cf4@gmail.com |
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| Lists: | pgsql-hackers |
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
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