Re: ExecForceStoreMinimalTuple leaks memory like there's no tomorrow

From: Michael Paquier <michael(at)paquier(dot)xyz>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: ExecForceStoreMinimalTuple leaks memory like there's no tomorrow
Date: 2019-04-16 03:31:37
Message-ID: 20190416033137.GB2673@paquier.xyz
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On Mon, Apr 15, 2019 at 10:46:56PM -0400, Tom Lane wrote:
> create table t1 as select generate_series(1,40000000) id;
> vacuum analyze t1;
> explain select * from t1, t1 t1b where t1.id = t1b.id;
> -- should indicate a hash join
> explain analyze select * from t1, t1 t1b where t1.id = t1b.id;
>
> ... watch the process's memory consumption bloat. (It runs for
> awhile before that starts to happen, but eventually it goes to
> a couple of GB.)
>
> It looks to me like the problem is that ExecHashJoinGetSavedTuple
> calls ExecForceStoreMinimalTuple with shouldFree = true, and
> ExecForceStoreMinimalTuple's second code branch simply ignores
> the requirement to free the supplied tuple.

Open item added, as the root comes from 4da597ed.
--
Michael

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