| From: | Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
|---|---|
| To: | Alena Rybakina <a(dot)rybakina(at)postgrespro(dot)ru> |
| Cc: | Nikolay Shaplov <dhyan(at)nataraj(dot)su>, pgsql-hackers(at)lists(dot)postgresql(dot)org, Andrei Lepikhov <a(dot)lepikhov(at)postgrespro(dot)ru>, jian he <jian(dot)universality(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org, Peter Geoghegan <pg(at)bowt(dot)ie>, "Finnerty, Jim" <jfinnert(at)amazon(dot)com>, Marcos Pegoraro <marcos(at)f10(dot)com(dot)br>, teodor(at)sigaev(dot)ru, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, Peter Eisentraut <peter(at)eisentraut(dot)org>, Ranier Vilela <ranier(dot)vf(at)gmail(dot)com> |
| Subject: | Re: POC, WIP: OR-clause support for indexes |
| Date: | 2024-07-27 10:56:40 |
| Message-ID: | CAPpHfdvUEjkuFNUbg7GuLkXotwvpDgBYz4S8YcE=LRf9aBQh-Q@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Jul 25, 2024 at 5:04 PM Alena Rybakina
<a(dot)rybakina(at)postgrespro(dot)ru> wrote:
> To be honest, I have found a big problem in this patch - we try to perform the transformation every time we examime a column:
>
> for (indexcol = 0; indexcol < index->nkeycolumns; indexcol++) { ...
>
> }
>
> I have fixed it and moved the transformation before going through the loop.
What makes you think there is a problem? Do you have a test case
illustrating a slow planning time?
When v27 performs transformation for a particular column, it just
stops facing the first unmatched OR entry. So,
match_orclause_to_indexcol() examines just the first OR entry for all
the columns excepts at most one. So, the check
match_orclause_to_indexcol() does is not much slower than other
match_*_to_indexcol() do.
I actually think this could help performance in many cases, not hurt
it. At least we get rid of O(n^2) complexity over the number of OR
entries, which could be very many.
------
Regards,
Alexander Korotkov
Supabase
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