On 2016-11-22 15:49:27 -0500, Robert Haas wrote:
> I think you are almost right.  When the server is running, there are
> files in pg_stat_tmp but not pg_stat; when it is shut down, there are
> files in pg_stat but not pg_stat_tmp.  Of course the data can never be
> ONLY in the collector's backend-local memory because then nobody else
> could read it.

> I don't actually really understand the reason for this distinction.

pg_stat_tmp commonly is placed on tmpfs/a ramdisk.

But I'm a bit confused too - does this make any sort of difference?
Because the startup path for crash recovery is like this:

        /* REDO */
        if (InRecovery)
                 * Reset pgstat data, because it may be invalid after recovery.

so it seems quite inconsequential whether we write out pgstat, because
we're going to nuke it either way after an immediate shutdown?


Andres Freund

Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:

Reply via email to