Re: Increase Vacuum ring buffer.

Good day, Claudio

On 2017-07-22 00:27, Claudio Freire wrote:
> On Fri, Jul 21, 2017 at 2:41 PM, Sokolov Yura
> <funny(dot)falcon(at)postgrespro(dot)ru> wrote:
>>
>> My friend noticed, that I didn't said why I bother with autovacuum.
>> Our customers suffers from table bloating. I've made synthetic
>> bloating test, and started experiments with modifying micro- and
>> auto-vacuum. My first attempts were to update FSM early (both in
>> micro and autovacuum) and update it upto root, not only low level.
>
> This FSM thing is probably not a bad idea as well.
>
> We're forced to run regular manual vacuums because for some tables
> autovacuums seems to never be enough, no matter how it's configured,
> mostly because it gets canceled all the time. These are high-churn,
> huge tables, so vacuuming them takes hours or days, there's always
> someone with a conflicting lock at some point that ends up canceling
> the autovacuum task.
>
> The above paragraph triggered me to go check, and it seems in those
> cases the FSM never gets vacuumed. That's probably not a good thing,
> but I don't see how to vacuum the FSM after a cancel. So vacuuming the
> FSM from time to time during long-running vacuums seems like a good
> idea at this point.

Attached patch changes fsm update: instead of updating only lowest
level, it propagates space increase up to root.

It slows autovacuum a bit, so that I didn't propose it together with
ring buffer increase.

--
Sokolov Yura aka funny_falcon
Postgres Professional: https://postgrespro.ru
The Russian Postgres Company