On 11/7/19 12:56 PM, Kyotaro Horiguchi wrote:
At Thu, 7 Nov 2019 12:22:28 +0300, Grigory Smolkin <g.smol...@postgrespro.ru>
wrote in
On 11/7/19 8:36 AM, Kyotaro Horiguchi wrote:
At Thu, 7 Nov 2019 02:28:39 +0300, Grigory Smolkin
<g.smol...@postgrespro.ru> wrote in
On 11/6/19 1:55 PM, Grigory Smolkin wrote:
On 11/6/19 12:56 PM, Fujii Masao wrote:
What happens if this parameter is set to latest in the standby mode?
Or the combination of those settings should be prohibited?
Currently it will behave just like regular standby, so I think, to
avoid confusion and keep things simple, the combination of them should
be prohibited.
Thank you for pointing this out, I will work on it.
Attached new patch revision, now it is impossible to use
recovery_target 'latest' in standby mode.
TAP test is updated to reflect this behavior.
In the first place, latest (or anything it could be named as) is
defined as the explit label for the default behavior. Thus the latest
should work as if nothing is set to recovery_target* following the
definition. That might seems somewhat strange but I think at least it
is harmless.
Well, it was more about getting default behavior by using some
explicit recovery_target, not the other way around. Because it will
break some 3rd party backup and replication applications, that may
rely on old behavior of ignoring recovery_target_action when no
recovery_target is provided.
But you think that it is worth pursuing, I can do that.
Ah. Sorry for the misleading statement. What I had in my mind was
somewhat the mixture of them. I thought that recovery_target =''
behaves the same way as now, r_t_action is ignored. And 'latest' just
makes recovery_target_action work as the current non-empty
recovery_target's does. But I'm not confident that it is a good
design.
recovery_target=immediate + r_t_action=shutdown for a standby works as
commanded. Do we need to inhibit that, too?
Why something, that work as expected, should be inhibited?
To make sure, I don't think we should do that. I meant by the above
that standby mode is already accepting recovery_target_action so
inhibiting that only for 'latest' is not orthogonal and could be more
confusing for users, and complicatig the code. So my opinion is we
shouldn't inhibit 'latest' unless r_t_action harms.
I gave it some thought and now think that prohibiting recovery_target
'latest' and standby was a bad idea.
All recovery_targets follow the same pattern of usage, so
recovery_target "latest" also must be capable of working in standby mode.
All recovery_targets have a clear deterministic 'target' where recovery
should end.
In case of recovery_target "latest" this target is the end of available
WAL, therefore the end of available WAL must be more clearly defined.
I will work on it.
Thank you for a feedback.
regards.
--
Grigory Smolkin
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
