Re: Logging WAL when updating hintbit

On Tue, Dec 3, 2013 at 5:34 PM, Sawada Masahiko <sawada(dot)mshk(at)gmail(dot)com> wrote:
> On Tue, Dec 3, 2013 at 4:28 PM, Michael Paquier
> <michael(dot)paquier(at)gmail(dot)com> wrote:
>> On Tue, Dec 3, 2013 at 3:30 PM, Sawada Masahiko <sawada(dot)mshk(at)gmail(dot)com> wrote:
>>
>> After more thinking...
>> Before performing a rewind on a node, what we need to know is that
>> log_hint_bits was set to true when WAL forked, because of the issue
>> that Robert mentioned here:
>> http://www.postgresql.org/message-id/519E5493.5060800@vmware.com
>> It does not really matter if the node used log_hint_bits set to false
>> in its latest state (Node to-be-rewinded might have been restarted
>> after WAL forked).
>>
>> So, after more thinking, yes using XLOG_PARAMETER_CHANGE and
>> PGC_POSTMASTER for this parameter would be enough. However on the
>> pg_rewind side we would need to track the value of log_hint_bits when
>> analyzing the WALs and ensure that it was set to true at fork point.
>> This is not something that the core should about though.
>
> Yep, pg_rewind needs to track the value of wal_log_hintbits.
> I think value of wal_log_hintbits always needs to have been set true
> after fork point.
> And if wal_log_hintbits is set false when we perform pg_rewind, we can not that.
>

I attached the patch which have modified based on Robert suggestion,
and fixed typo.

Regards,

-------
Sawada Masahiko