From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
---|---|
To: | Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> |
Cc: | Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Pavan Deolasee <pavan(dot)deolasee(at)2ndquadrant(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com> |
Subject: | Re: speeding up planning with partitions |
Date: | 2018-09-11 01:11:15 |
Message-ID: | CAH2-WznUbJx8OKohHcetyWQRy4LXEfbpTcAGFvc5K6i1BSG40w@mail.gmail.com |
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On Wed, Aug 29, 2018 at 5:06 AM, Amit Langote
<Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> It is more or less well known that the planner doesn't perform well with
> more than a few hundred partitions even when only a handful of partitions
> are ultimately included in the plan. Situation has improved a bit in PG
> 11 where we replaced the older method of pruning partitions one-by-one
> using constraint exclusion with a much faster method that finds relevant
> partitions by using partitioning metadata. However, we could only use it
> for SELECT queries, because UPDATE/DELETE are handled by a completely
> different code path, whose structure doesn't allow it to call the new
> pruning module's functionality. Actually, not being able to use the new
> pruning is not the only problem for UPDATE/DELETE, more on which further
> below.
This was a big problem for the SQL MERGE patch. I hope that this
problem can be fixed.
--
Peter Geoghegan
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