| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Jack Orenstein <jack(dot)orenstein(at)hds(dot)com> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Table bloat and vacuum |
| Date: | 2008-11-12 15:19:23 |
| Message-ID: | 20081112151923.GF4535@alvh.no-ip.org |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
Jack Orenstein wrote:
> 1) Why does the tiny table bloat during a vacuum? Is it because the
> scan of the huge table is run as a transaction, forcing maintenance of
> dead versions of the tiny table's one row?
Yes.
> 2) Why does the bloat resolve itself? We're not doing any full
> vacuums.
Probably the one live tuple bounces to the first page at some point and
then the rest of the pages are truncated by vacuum.
> We're in the process of upgrading to 8.3.4, so I'd appreciate any
> throughs on whether and how this behavior will change with the newer
> release.
In 8.3, vacuuming the big table will not delay dead tuple removal of the
small table.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Sergey Konoplev | 2008-11-12 15:23:16 | Re: Very slow queries w/ NOT IN preparation (seems like a bug, test case) |
| Previous Message | Markus Wollny | 2008-11-12 15:15:23 | Suboptimal execution plan for simple query |