| From: | "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> |
|---|---|
| To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | "Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com>, <pgsql-hackers(at)postgreSQL(dot)org> |
| Subject: | Re: HOT is applied |
| Date: | 2007-09-20 19:22:26 |
| Message-ID: | 46F2C872.20108@enterprisedb.com |
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| Lists: | pgsql-hackers |
Tom Lane wrote:
> I've committed the HOT patch.
Thanks, much easier to work with it now that it's in.
> I'd still like to think about whether we
> can be smarter about when to invoke pruning, but that's a small enough
> issue that the patch can go in without it.
Yeah. I'm doing some micro-benchmarking, and the attached test case is
much slower with HOT. It's spending a lot of time trying to prune, only
to find out that it can't.
Instead of/in addition to avoiding pruning when it doesn't help, maybe
we could make HeapTupleSatisfiesVacuum cheaper.
I'm going to continue testing, this is just a heads-up that HOT as
committed seriously hurts performance in some cases. (though one can
argue that this test case isn't a very realistic one.)
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
| Attachment | Content-Type | Size |
|---|---|---|
| updatetest-2.sql | text/x-sql | 430 bytes |
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