Re: WAL Queries

On 8/5/07, Paul Lambert <paul.lambert@autoledgers.com.au> wrote:
> RPK wrote:
> > Before modifying postgresql.conf, do I need to stop PGSQL service?
> >
> >
> >> Enable it in the "Write Ahead Log" section of postgresql.conf file in
> >> the PGDATA directory.
> >
>
> You need to restart PostgreSQL after the file has been modified - it
> does not need to be shut down whilst the modification is being
> undertaken, just a quick restart once you have saved the file.

This is not quite correct: you may change archive_command in
postgresql.conf and do a pg_ctl reload to bring in the setting without
a full restart of the server.

Also, I wold like to make a small clarification: In PostgreSQL, WAL is
always on and there is no way to turn it off....the archive_command
allows you to intercept the WAL files as they are written to disk and
do additional things with them.  Normally this would involve directing
them to storage or a standby server.  Saving off WAL files is only
useful if you take a filesystem snapshot of the database first...the
pg_start_backup facilitates this.

merlin