| From: | Gregory Stark <stark(at)enterprisedb(dot)com> |
|---|---|
| To: | "Andrew Dunstan" <andrew(at)dunslane(dot)net> |
| Cc: | "Bruce Momjian" <bruce(at)momjian(dot)us>, "Josh Berkus" <josh(at)agliodbs(dot)com>, "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>, "PostgreSQL-development" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: MVCC, undo log, and HOT |
| Date: | 2007-10-23 08:35:22 |
| Message-ID: | 87y7dufctx.fsf@oxford.xeocode.com |
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| Lists: | pgsql-hackers |
"Andrew Dunstan" <andrew(at)dunslane(dot)net> writes:
> HOT is cool, but it really doesn't solve the whole problem. It works for a
> significant class of problems, but for example it won't have any significant
> effect on the app I'm currently working on which is very index-rich. It would
> be a major mistake to think there's no work left to do in improving update
> performance.
Another use case it doesn't address is updating a large fraction of the table.
If you do a single unconstrained "UPDATE foo SET x=y" your table and indexes
will double in size and never shrink back.
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
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