Re: Writing WAL files

On 10/4/20 9:54 AM, Robert Inder wrote:
> I am moving a database from PSQL 9 (!) on CentOS 6 to PSQL 12 on CentOS 7

It would help to know what the x in 9.x is? Before version 10 of
Postgres, the second number denoted a major version.

>
> I have a pair of servers -- one live, one standby.
> The live server defines an archive_command as "rsync...." to shift WAL
> files to the standby server,
> The standby server uses "pg_standby" to monitor and process incoming WAL
> files.
> I believe this is all very vanilla, and indeed changes made in the live
> database are duly shipped to the standby.
>
> BUT...
>
> One of the things I like about the old PGSQL 9 setup is that it
> generates and ships a WAL file every few minutes, even if nothing has
> happened in the database.
> I find it re-assuring to be able to see WAL files arriving and being
> processed without problem even when the live system was idle.
>
> But I cannot get PGSQL 12 to do this.  It only writes (and thus ships)
> WAL files when something happens in the database.
> If the database is idle, it simply does not write any WAL files.
>
> I thought I would get WAL files written from an idle database if, in
> postgresql.conf, I set "archive_timeout" to 120.
>
> And I've tried setting "checkpoint_timeout" to 90s,
>
> But to no avail.  No WAL files are written unless the database changes.
>
> So what am I missing?  How CAN I get postgresql 12 to write
> "unnecessary" WAL files every couple of minutes?
>
> Robert.
>
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Adrian Klaver
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