Re: auto-sizing wal_buffers
Fujii Masao <masao.fujii@gmail.com>
From: Fujii Masao <masao.fujii@gmail.com>
To: Greg Smith <greg@2ndquadrant.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>, Magnus Hagander <magnus@hagander.net>, pgsql-hackers@postgresql.org
Date: 2011-01-17T01:07:16Z
Lists: pgsql-hackers
On Sun, Jan 16, 2011 at 1:52 AM, Greg Smith <greg@2ndquadrant.com> wrote: > Fujii Masao wrote: >> >> +int XLOGbuffersMin = 8; >> >> XLOGbuffersMin is a fixed value. I think that defining it as a macro >> rather than a variable seems better. >> >> + if (XLOGbuffers > 2048) >> + XLOGbuffers = 2048; >> >> Using "XLOG_SEG_SIZE/XLOG_BLCKSZ" rather than 2048 seems >> better. >> >> +#wal_buffers = -1 # min 32kB, -1 sets based on >> shared_buffers >> >> Typo: s/32kB/64kB >> > > Thanks, I've fixed all these issues and attached a new full patch, pushed to > github, etc. Tests give same results back, and it's nice that it scale to > reasonable behavior if someone changes their XLOG segment size. Thanks for the update. +/* Minimum setting used for a lower bound on wal_buffers */ +#define XLOG_BUFFER_MIN 4 Why didn't you use XLOG_BUFFER_MIN instead of XLOGbuffersMin? XLOG_BUFFER_MIN is not used anywhere for now. + if (XLOGbuffers < (XLOGbuffersMin * 2)) + XLOGbuffers = XLOGbuffersMin * 2; + } Why is the minimum value 64kB only when wal_buffers is set to -1? This seems confusing for users. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center