Re: Patch for fail-back without fresh backup

On Tue, Jun 25, 2013 at 12:19 PM, Pavan Deolasee
<pavan(dot)deolasee(at)gmail(dot)com> wrote:
>
>
>
> On Mon, Jun 24, 2013 at 7:17 PM, Sawada Masahiko <sawada(dot)mshk(at)gmail(dot)com>
> wrote:
>>
>>
>>
>> --------------------
>> [Server]
>> standby_name = 'slave1'
>> synchronous_transfer = commit
>> wal_sender_timeout = 30
>> [Server]
>> standby_name = 'slave2'
>> synchronous_transfer = all
>> wal_sender_timeout = 50
>> -------------------
>
>
> What different values/modes you are thinking for synchronous_transfer ? IMHO
> only "commit" and "all" may not be enough. As I suggested upthread, we may
> need an additional mode, say "data", which will ensure synchronous WAL
> transfer before making any file system changes. We need this separate mode
> because the failback safe (or whatever we call it) standby need not wait on
> the commits and it's important to avoid that wait since it comes in a direct
> path of client transactions.
>
> If we are doing it, I wonder if an additional mode "none" also makes sense
> so that users can also control asynchronous standbys via the same mechanism.

I made mistake how to use name of parameter between
synchronous_transfer and failback_safe_standby_mode.
it means that we control file system changes using
failback_safe_standby_mode. if failback_safe_standby_mode is set
'remote_flush', master server wait for flushing all data page in
standby server (e.g., CLOG, pg_control).
right?
for example:
------
[server]
standby_name = 'slave1'
failback_safe_standby_mode = remote_flush
wal_sender_timeout = 50
------

in this case, we should also set synchronous_commit and
synchronous_level to each standby server. that is, do we need to set
following 3 parameters for supporting case 3,4 as I said?
-synchronous_commit = on/off/local/remote_write
-failback_safe_standby_mode = off/remote_write/remote_flush
-synchronous_level = sync/async (this parameter means that standby
server is connected using which mode (sync/async) .)

please give me your feedback.

Regards,
-------
Sawada Masahiko