| From: | "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com> |
|---|---|
| To: | "Mark Woodward" <pgsql(at)mohawksoft(dot)com> |
| Cc: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Csaba Nagy" <nagy(at)ecircle-ag(dot)com>, "Hannu Krosing" <hannu(at)skype(dot)net>, "Christopher Browne" <cbbrowne(at)acm(dot)org>, "postgres hackers" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: vacuum, performance, and MVCC |
| Date: | 2006-06-23 19:12:42 |
| Message-ID: | 36e682920606231212r1436ba97q47ab8abf18f5b6d2@mail.gmail.com |
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| Lists: | pgsql-hackers |
On 6/23/06, Mark Woodward <pgsql(at)mohawksoft(dot)com> wrote:
> Rather than keep references to all versions of all
> rows in indexes, keep only a reference to the first or "key" row of each
> row, and have the first version of a row form the head of a linked list to
> subsequent versions of each row. The list will be in decending order.
By all means, please go ahead and try it because it's not quite that
easy. You're going to run into serious locking and contention issues
this way. In the end, it's not much better than running a sequential
scan to query a row that's been updated several thousand times on a
table that hasn't been vacuumed... follow that pointer :)
--
Jonah H. Harris, Software Architect | phone: 732.331.1300
EnterpriseDB Corporation | fax: 732.331.1301
33 Wood Ave S, 2nd Floor | jharris(at)enterprisedb(dot)com
Iselin, New Jersey 08830 | http://www.enterprisedb.com/
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