| From: | "Simon Riggs" <simon(at)2ndquadrant(dot)com> |
|---|---|
| To: | "ITAGAKI Takahiro" <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> |
| Cc: | <pgsql-patches(at)postgresql(dot)org> |
| Subject: | Re: Dead Space Map patch |
| Date: | 2006-12-28 19:40:30 |
| Message-ID: | 1167334830.3633.177.camel@silverbirch.site |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-patches |
On Thu, 2006-12-28 at 15:14 +0900, ITAGAKI Takahiro wrote:
> Even if it is off, DSM are always recorded and updated.
The purpose of the patch, as I understand it, is performance.
Can I ask what the performance overhead of this is for standard OLTP
workloads?
Do you have some performance numbers for VACUUM with/without this patch?
Presumably it does speed things up considerably, but question is, how
much?
Is there a point where you VACUUM more than x% of a table that it is
actually better to just VACUUM the whole thing, because of readahead?
Is there a size of table for which keeps dsm information is not
worthwhile? i.e. small tables
--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com
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