Re: autovacuum multiworkers, patch 5

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

Joshua D. Drake

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