On 03/02/15 13:51, Magnus Hagander wrote:
On Tue, Feb 3, 2015 at 1:43 PM, Andres Freund <and...@2ndquadrant.com
<mailto:and...@2ndquadrant.com>> wrote:
Hi,
I think these days there's no reason for the split between the archive
and hot_standby wal levels. The split was made out of volume and
stability concerns. I think we can by now be confident about the
wal_level = hot_standby changes (note I'm not proposing hot_standby =
on).
So let's remove the split. It just gives users choice between two
options
that don't have a meaningful difference.
+1.
+1 too
Additionally I think we should change the default for wal_level to
hot_standby and max_wal_senders (maybe to 5). That way users can use
pg_basebackup and setup streaming standbys without having to restart the
primary. I think that'd be a important step in making setup easier.
Yes, please!
Those who want to optimize their WAL size can set it back to minimal,
but let's make the default the one that makes life *easy* for people.
The other option, which would be more complicated (I have a
semi-finished patch that I never got time to clean up) would be for
pg_basebackup to be able to dynamically raise the value of wal_level
during it's run. It would not help with the streaming standby part, but
it would help with pg_basebackup. That could be useful independent - for
those who prefer using wal_level=minimal and also pg_basebackup..
This is not that easy to do, let's do it one step at a time.
Comments?
Additionally, more complex and further into the future, I wonder if we
couldn't also get rid of wal_level = logical by automatically switching
to it whenever logical slots are active.
If it can be safely done online, I definitely think that would be a good
goal to have. If we could do the same for hot_standby if you had
physical slots, that might also be a good idea?
+many for the logical, physical would be nice but I think it's again in
the category of not so easy and maybe better as next step if at all.
--
Petr Jelinek http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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