Re: Strange issues with 9.2 pg_basebackup & replication

On 15 May 2012 13:15, Fujii Masao <masao.fujii@gmail.com> wrote:
> On Wed, May 16, 2012 at 1:36 AM, Thom Brown <thom@linux.com> wrote:
>> However, this isn't true when I restart the standby.  I've been
>> informed that this should work fine if a WAL archive has been
>> configured (which should be used anyway).
>
> The WAL archive should be shared by master-replica and replica-replica,
> and recovery_target_timeline should be set to latest in replica-replica.
> If you configure that way, replica-replica would successfully reconnect to
> master-replica with no need to restart it.

I had set the archive_command on the primary, then produced a base
backup which would have copied the archive settings, but I also added
a corresponding recovery_command setting, so everything was pointing
at the same archive.

>> But one new problem I appear to have is that once I set up archiving
>> and restart, then try pg_basebackup, it gets stuck and never shows any
>> progress.  If I terminate pg_basebackup in this state and attempt to
>> restart it more times than max_wal_senders, it can no longer run, as
>> pg_basebackup didn't disconnect the stream, so ends up using all
>> senders.  And these show up in pg_stat_replication.  I have a theory
>> that if archiving is enabled, restart postgres then generate some WAL
>> to the point there is a file or two in the archive, pg_basebackup
>> can't stream anything.  Once I restart the server, it's fine and
>> continues as normal.  This has the same symptoms of the "pg_basebackup
>> from running standby with streaming" issue.
>
> This seems to be caused by spread checkpoint which is requested by
> pg_basebackup. IOW, this looks a normal behavior rather than a bug
> or an issue. What if you specify "-c fast" option in pg_basebackup?

Yes, it works fine with that option.  And it appears this isn't to do
with there being an archive as I get the same symptoms without setting
one up.  But in any case, shouldn't the replication connection be
terminated when pg_basebackup is terminated?

--
Thom