| 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: | 2008-03-11 13:06:33 |
| Message-ID: | 2e78013d0803110606hb0eaa2aq1784608cf4c7026c@mail.gmail.com |
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| Lists: | pgsql-patches pgsql-performance |
On Tue, Mar 11, 2008 at 6:04 PM, Heikki Linnakangas
<heikki(at)enterprisedb(dot)com> wrote:
> (moved to pgsql-patches, as there's a patch attached)
>
>
> I couldn't let this case go, so I wrote a patch. I replaced the linked
> list with an array that's enlarged at AtSubCommit_childXids when necessary.
>
We can replace the array of xids with an array of flags where i'th flag is
set to true if the corresponding subtransaction is committed. This would
make lookup O(1) operation. Of course, the downside is when the array
is sparse. Or we can switch to flag based representation once the array size
grows beyond a limit.
Thanks,
Pavan
--
Pavan Deolasee
EnterpriseDB http://www.enterprisedb.com
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