Re: Table-level log_autovacuum_min_duration

Michael Paquier wrote:

> In AutoVacWorkerMain, I am reading the following:
>
> * Currently, we don't pay attention to postgresql.conf changes that
> * happen during a single daemon iteration, so we can ignore SIGHUP.
> */
> pqsignal(SIGHUP, SIG_IGN);
>
> So a worker does not see changes in postgresql.conf once it is run and
> processes a database, no? The launcher does run ProcessConfigFile()
> when SIGHUP shows up though.

Maybe this is something that we should change. For example, I wonder if
this can also affect the cost-delay balancing heuristics; if two
backends run the rebalance with different GUC settings because
postgresql.conf changed in between each of them starting, would the
settings bounce back and forth. I think it's worth reconsidering this.
(Don't really remember in detail how it works; maybe it's fine now.)

In any case, for log_autovacuum_min_duration it also seems worth keeping
reasonably close track of GUC changes. I think reading them just before
starting vacuum of a new relation should be enough.

--
Álvaro Herrera http://www.2ndQuadrant.com/
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