Re: autovacuum multiworkers, patch 5

Joshua D. Drake wrote:
> Alvaro Herrera wrote:
> >ITAGAKI Takahiro wrote:
> >>Alvaro Herrera <alvherre@commandprompt.com> wrote:
> >>
> >>>Here is the autovacuum patch I am currently working with.  This is
> >>>basically the same as the previous patch; I have tweaked the database
> >>>list management so that after a change in databases (say a new database
> >>>is created or a database is dropped), the list is recomputed to account
> >>>for the change, keeping the ordering of the previous list.
> >>I'm interested in your multiworkers autovacuum proposal.
> >>
> >>I'm researching the impact of multiworkers with
> >>autovacuum_vacuum_cost_limit.
> >>Autovacuum will consume server resources up to autovacuum_max_workers
> >>times
> >>as many as before. I think we might need to change the semantics of
> >>autovacuum_vacuum_cost_limit when we have multiworkers.
> >
> >Yes, that's correct.  Per previous discussion, what I actually wanted to
> >do was to create a GUC setting to simplify the whole thing, something
> >like "autovacuum_max_mb_per_second" or "autovacuum_max_io_per_second".
> >Then, have each worker use up to (max_per_second/active workers) as much
> >IO resources.  This way, the maximum use of IO resources by vacuum can
> >be easily determined and limited by the DBA; certainly much simpler than
> >the vacuum cost limiting feature.
>
> +1

One thing I forgot to mention is that this is unlikely to be implemented
in 8.3.

--
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.