Re: Tuplestore should remember the memory context it's created in

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Greg Stark <gsstark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Tuplestore should remember the memory context it's created in
Date: 2009-12-22 16:13:24
Message-ID: 4B30F024.2070808@enterprisedb.com
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Tom Lane wrote:
> Greg Stark <gsstark(at)mit(dot)edu> writes:
>> On Tue, Dec 22, 2009 at 11:45 AM, Heikki Linnakangas
>> <heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
>>> AFAICS it is always a bug to be in a different memory context
>>> in tuplestore_put* than in tuplestore_begin_heap(), so it would be more
>>> robust to not put the burden on the callers.
>
>> I thought there were comments specifically explaining why it was done
>> that way but I don't recall what they said.
>
> I think it was just a performance optimization. It's probably not
> measurable though; even in the in-memory case there's at least a palloc
> inside the put() function, no?

Yes. And many of the callers do the memory context switching dance anyway.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

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