| From: | Bruce Momjian <bruce(at)momjian(dot)us> |
|---|---|
| To: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
| Cc: | Hannu Krosing <hannu(at)skype(dot)net>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Greg Stark <gsstark(at)mit(dot)edu>, PFC <lists(at)peufeu(dot)com> |
| Subject: | Re: Single Index Tuple Chain (SITC) method |
| Date: | 2006-06-29 18:54:01 |
| Message-ID: | 200606291854.k5TIs1V01894@momjian.us |
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| Lists: | pgsql-hackers |
Martijn van Oosterhout wrote:
> One thing I am confused about, currently the ctid chain follows tuple
> history so that transactions can find the latest version of any tuple,
> even if the key fields have changed. This proposal breaks that, I'm not
> sure how important that is though.
No, SITC doesn't break the UPDATE chain, it merely doesn't set the
SITC_NOT_TAIL bit on the tuple, so an index scan knows that is the last
tuple for that index entry.
--
Bruce Momjian bruce(at)momjian(dot)us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
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