Re: 9.5: Better memory accounting, towards memory-bounded HashAgg

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: 9.5: Better memory accounting, towards memory-bounded HashAgg
Date: 2014-08-10 20:50:16
Message-ID: 1407703816.6623.2.camel@jeff-desktop
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On Fri, 2014-08-08 at 01:16 -0700, Jeff Davis wrote:
> Either way, it's better to be conservative. Attached is a version of the
> patch with opt-in memory usage tracking. Child contexts inherit the
> setting from their parent.

There was a problem with the previous patch: the parent was unlinked
before the delete_context method was called, which meant that the
parent's memory was not being decremented.

Attached is a fix. It would be simpler to just reorder the operations in
MemoryContextDelete, but there is a comment warning against that. So, I
pass the old parent as an argument to the delete_context method.

Jeff Davis

Attachment Content-Type Size
memory-accounting-v3.patch text/x-patch 12.8 KB

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