| From: | Jeff Davis <pgsql(at)j-davis(dot)com> |
|---|---|
| To: | Rich Shepard <rshepard(at)appl-ecosys(dot)com> |
| Cc: | pdxpug(at)postgresql(dot)org |
| Subject: | Re: pre-algebra discussion - HOT? |
| Date: | 2007-09-20 21:10:18 |
| Message-ID: | 1190322618.5943.80.camel@dogma.ljc.laika.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pdxpug |
On Thu, 2007-09-20 at 13:22 -0700, Rich Shepard wrote:
> On Thu, 20 Sep 2007, Jeff Davis wrote:
>
> > I've been following HOT for a while, and I don't mind sharing. I do not
> > have in-depth knowledge on it, however.
>
> Jeff/Selena,
>
> For those of us who are NOT HOT, please explain what HOT is/does. In two
> sentences.
>
HOT stands for Heap Only Tuple, and refers to a an updated version of a
tuple that shares the index entry with the original version of the
tuple. This only works for UPDATEs which do not change any indexed
columns, but it allows retail (page-at-a-time) space reclamation
(VACUUM) which drastically reduces table and index bloat and improves
efficiency under heavy UPDATE load.
Regards,
Jeff Davis
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