Re: Online base backup from the hot-standby
Fujii Masao <masao.fujii@gmail.com>
From: Fujii Masao <masao.fujii@gmail.com>
To: Simon Riggs <simon@2ndquadrant.com>
Cc: Jun Ishiduka <ishizuka.jun@po.ntts.co.jp>, ssinger_pg <ssinger_pg@sympatico.ca>, magnus <magnus@hagander.net>, robertmhaas <robertmhaas@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, "cedric.villemain.debian" <cedric.villemain.debian@gmail.com>, "heikki.linnakangas" <heikki.linnakangas@enterprisedb.com>
Date: 2011-10-13T13:44:50Z
Lists: pgsql-hackers
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