On Mon, Oct 10, 2011 at 3:56 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
> 2011/10/9 Jun Ishiduka <ishizuka.jun@po.ntts.co.jp>:
>
>> Insert WAL including a value of current FPW (on master)
>> * In the the same timing as update, they insert WAL (is named
>> XLOG_FPW_CHANGE). XLOG_FPW_CHANGE has a value of the changed FPW.
>> * When it creates CHECKPOINT, it adds a value of current FPW to the
>> CHECKPOINT WAL.
>
> I can't see a reason why we would use a new WAL record for this,
> rather than modify the XLOG_PARAMETER_CHANGE record type which was
> created for a very similar reason.
> The code would be much simpler if we just extend
> XLOG_PARAMETER_CHANGE, so please can we do that?
After reading Ishiduka-san's patch, I'm thinking the opposite because
(1) Whenever full_page_writes must be WAL-logged, there is no need
to WAL-log the HS parameters. The opposite is also true. (2) How
full_page_writes record should be replayed is quite different from
how HS parameters record is.
So ISTM that the code would be simpler if we introduce new WAL
record for full_page_writes. Thought?
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center