Re: Subplan result caching

From: Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>
To: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Subplan result caching
Date: 2018-05-23 10:03:30
Message-ID: 1527069810.7039.1.camel@cybertec.at
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Heikki Linnakangas wrote:
> I've been working on a patch to add a little cache to SubPlans, to speed
> up queries with correlated subqueries, where the same subquery is
> currently executed multiple times with the same parameters. The idea is
> to cache the result of the subplan, with the correlation vars as the
> cache key.

I like the idea.

I think the cache should be limited in size, perhaps by work_mem.
Also, there probably should be a GUC for this, defaulting to "off".

Yours,
Laurenz Albe

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