Re: Patch for fail-back without fresh backup

On Tue, Sep 17, 2013 at 9:52 PM, Fujii Masao <masao.fujii@gmail.com> wrote:
> On Tue, Sep 17, 2013 at 3:45 PM, Samrat Revagade
> <revagade.samrat@gmail.com> wrote:
>>
>>> > syncrep.c: In function ‘SyncRepReleaseWaiters’:
>>> > syncrep.c:421:6: warning: variable ‘numdataflush’ set but not used
>>> > [-Wunused-but-set-variable]
>>> >
>>>
>>> Sorry I forgot fix it.
>>>
>>> I have attached the patch which I modified.
>>>
>>
>> Attached patch combines documentation patch and source-code patch.
>
> 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?
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.

>
> 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.

Regards,

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Sawada Masahiko