| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Gregory Stark <stark(at)enterprisedb(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org, pgsql-patches(at)postgresql(dot)org |
| Subject: | Re: [HACKERS] WAL logging freezing |
| Date: | 2006-10-31 19:56:59 |
| Message-ID: | 20061031195659.GD12008@alvh.no-ip.org |
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| Lists: | pgsql-hackers pgsql-patches |
Gregory Stark wrote:
>
> "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
>
> > The added WAL volume should be pretty minimal, because only tuples that have
> > gone untouched for a long time incur extra work.
>
> That seems like a weak point in the logic. It seems like it would make VACUUM
> which is already an i/o hog even more so. Perhaps something clever can be done
> with vacuum_cost_delay and commit_siblings.
>
> Something like inserting the delay between WAL logging and syncing the log and
> writing to the heap. So if another transaction commits in the meantime we can
> skip the extra fsync and continue.
Huh, but the log would not be flushed for each operation that the vacuum
logs. Only when it's going to commit.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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