| From: | "Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com> |
|---|---|
| To: | "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com> |
| Cc: | "Bruce Momjian" <bruce(at)momjian(dot)us>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Florian Pflug" <fgp(dot)phlo(dot)org(at)gmail(dot)com>, "Simon Riggs" <simon(at)2ndquadrant(dot)com>, "Gregory Stark" <stark(at)enterprisedb(dot)com>, PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org> |
| Subject: | Re: HOT patch - version 15 |
| Date: | 2007-09-10 19:15:34 |
| Message-ID: | 2e78013d0709101215r5b92be68ifaa0fde92cafd3ee@mail.gmail.com |
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| Lists: | pgsql-patches |
On 9/10/07, Heikki Linnakangas <heikki(at)enterprisedb(dot)com> wrote:
>
>
> Oh, one more thing occured to me. Without HOT, we not only mark index
> tuples pointing to dead tuples as killed, we remove them altogether if
> the index page gets full. If you modify the test case so that after
> doing the updates, you insert a bunch of tuples with a different key to
> fill the index page, you should see CVS HEAD winning HOT without pruning
> hands down.
>
>
Um. I am not sure I follow that. With HOT even if the HOT chain is long,
there is still just one index entry for the entire chain. So I don't see
why CVS HEAD would do better than HOT in the above case. Net-net
there will be equal number of index keys after the inserts.
Thanks,
Pavan
--
Pavan Deolasee
EnterpriseDB http://www.enterprisedb.com
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