Robert Haas wrote:
> On Mon, Apr 12, 2010 at 6:41 AM, Heikki Linnakangas
> <heikki.linnakangas@enterprisedb.com> wrote:
>>> Why is standby_keep_segments used even if max_wal_senders is zero?
>>> In that case, ISTM we don't need to keep any WAL files in pg_xlog
>>> for the standby.
>> True. I don't think we should second guess the admin on that, though.
>> Perhaps he only set max_wal_senders=0 temporarily, and will be
>> disappointed if the the logs are no longer there when he sets it back to
>> non-zero and restarts the server.
>
> If archive_mode is off and max_wal_senders = 0, then the WAL that's
> being generated won't be usable for streaming anyway, right?
>
> I think this is another manifestation of the problem I was complaining
> about over the weekend: there's no longer a single GUC that controls
> what type of information we emit as WAL. In previous releases,
> archive_mode served that function, but now it's much more complicated
> and, IMHO, not very comprehensible.
>
> http://archives.postgresql.org/pgsql-hackers/2010-04/msg00509.php
Agreed. We've been trying to deduce from other settings what information
needs to be WAL-logged, but it hasn't been a great success so it would
be better to make it explicit than try to hide it.
-- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com
