| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Florian Pflug <fgp(dot)phlo(dot)org(at)gmail(dot)com> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, Gregory Stark <stark(at)enterprisedb(dot)com>, PostgreSQL-patches <pgsql-patches(at)postgresql(dot)org> |
| Subject: | Re: HOT patch - version 15 |
| Date: | 2007-09-09 02:51:32 |
| Message-ID: | 10170.1189306292@sss.pgh.pa.us |
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| Lists: | pgsql-patches |
Florian Pflug <fgp(dot)phlo(dot)org(at)gmail(dot)com> writes:
> I was under the impression that pruning *does* free the space occupied
> by DEAD HOT-Tuples (minus the size of a redirection line pointer). It
> just doesn't defragment, so how much of that freed space you can actually
> use to store new tuples is another question...
None, unless the freed tuple happens to be directly adjacent to the
pd_lower --- pd_upper hole, or unless the patch has done a lot more to
the page-free-space-management code than I thought. We have never
looked for free space anywhere except the main "hole".
regards, tom lane
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