Re: ExecForceStoreMinimalTuple leaks memory like there's no tomorrow

Michael Paquier <michael@paquier.xyz>

From: Michael Paquier <michael@paquier.xyz>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>, pgsql-hackers@lists.postgresql.org
Date: 2019-04-16T03:31:37Z
Lists: pgsql-hackers
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

Commits

  1. Fix two memory leaks around force-storing tuples in slots.