Re: prevent immature WAL streaming - Mailing list pgsql-hackers

From Andres Freund
Subject Re: prevent immature WAL streaming
Date
Msg-id 20211013191345.gqgsih7gq6jn5cxo@alap3.anarazel.de
Whole thread Raw
In response to Re: prevent immature WAL streaming  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
Responses Re: prevent immature WAL streaming  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
Re: prevent immature WAL streaming  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
Hi,

On 2021-10-13 15:52:46 -0300, Alvaro Herrera wrote:
> > Hm. I guess we can disable autovac. But that's not a great solution, there
> > might be WAL files due to catalog access etc too.
> 
> Well, we don't expect anything else to happen -- the cluster is
> otherwise idle.  I think we should do it regardless of any other
> changes, just to keep things steadier.

IDK, it seems good to have a bit of variance as well. But I don't have a
strong opinion on it.


> > Another thing: filling a segment by inserting lots of very tiny rows is pretty
> > expensive. Can't we use something a bit wider? Perhaps even emit_message?

FWIW, the count of inserted rows is something like 171985 ;)


> I think I realized partway through writing the test that I could use
> emit_message instead of using a batched row insert ... so, yeah, we
> can use it here also.

Cool. Even if we want to use inserts, lets at least make the rows wide...

I think it'd be good to have a bit of variance in record width. So perhaps
adding a bit of random() in to influence record width would be a good idea?

Greetings,

Andres Freund



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