From: | "Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com> |
---|---|
To: | "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> |
Cc: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "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 17:26:22 |
Message-ID: | 2e78013d0803121026r227bbebdr5189be193b4a1bf5@mail.gmail.com |
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Lists: | pgsql-patches pgsql-performance |
On Wed, Mar 12, 2008 at 10:44 PM, Heikki Linnakangas
<heikki(at)enterprisedb(dot)com> wrote:
>
> Imagine that you start a transaction just before transaction
> wrap-around, so that the top level XID is 2^31-10. Then you start 20
> subtransactions. What XIDs will they get? Now how would you map those to
> a bitmap?
>
Wait. Subtransaction ids are local to a transaction and always start from 1.
See this:
/*
* reinitialize within-transaction counters
*/
s->subTransactionId = TopSubTransactionId;
currentSubTransactionId = TopSubTransactionId;
>
> It's not that common to have hundreds of thousands of subtransactions to
> begin with..
True. But thats the case we are trying to solve here :-)
Thanks,
Pavan
--
Pavan Deolasee
EnterpriseDB http://www.enterprisedb.com
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