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Re: [PERFORM] Very slow (2 tuples/second) sequential scan after bulk insert; speed returns to ~500 tuples/second after commit

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com>
Cc: "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com>, "Craig Ringer" <craig(at)postnewspapers(dot)com(dot)au>, pgsql-patches <pgsql-patches(at)postgresql(dot)org>
Subject: Re: [PERFORM] Very slow (2 tuples/second) sequential scan after bulk insert; speed returns to ~500 tuples/second after commit
Date: 2008-03-12 15:57:19
Message-ID: 19902.1205337439@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-patchespgsql-performance
"Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com> writes:
> On Wed, Mar 12, 2008 at 7:13 PM, Heikki Linnakangas
> <heikki(at)enterprisedb(dot)com> wrote:
>> Yep, patch attached. I also changed xactGetCommittedChildren to return
>> the original array instead of copying it, as Alvaro suggested.

> Any comments on the flag based approach I suggested earlier ?

I didn't like it; it seemed overly complicated (consider dealing with
XID wraparound), and it would have problems with a slow transaction
generating a sparse set of subtransaction XIDs.  I think getting rid of
the linear search will be enough to fix the performance problem.

			regards, tom lane

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