Re: Patch for fail-back without fresh backup

On Wed, Sep 18, 2013 at 10:35 AM, Sawada Masahiko <sawada(dot)mshk(at)gmail(dot)com> wrote:
> On Tue, Sep 17, 2013 at 9:52 PM, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
>> I set up synchronous replication with synchronous_transfer = all, and then I ran
>> pgbench -i and executed CHECKPOINT in the master. After that, when I executed
>> CHECKPOINT in the standby, it got stuck infinitely. I guess this was cased by
>> synchronous_transfer feature.
>
> Did you set synchronous_standby_names in the standby server?

Yes.

> If so, the master server waits for the standby server which is set to
> synchronous_standby_names.
> Please let me know detail of this case.

Both master and standby have the same postgresql.conf settings as follows:

max_wal_senders = 4
wal_level = hot_standby
wal_keep_segments = 32
synchronous_standby_names = '*'
synchronous_transfer = all

>> How does synchronous_transfer work with cascade replication? If it's set to all
>> in the "sender-side" standby, it can resolve the data page inconsistency between
>> two standbys?
>>
>
> Currently patch supports the case which two servers are set up SYNC replication.
> IWO, failback safe standby is the same as SYNC replication standby.
> User can set synchronous_transfer in only master side.

So, it's very strange that CHECKPOINT on the standby gets stuck infinitely.

Regards,

--
Fujii Masao