Re: checkpoints are duplicated even while the system is idle
Tom Lane <tgl@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Simon Riggs <simon@2ndQuadrant.com>
Cc: Fujii Masao <masao.fujii@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2011-10-06T16:06:04Z
Lists: pgsql-hackers
Simon Riggs <simon@2ndQuadrant.com> writes: > The current idea is that if there has been no activity then we skip > checkpoint. But all it takes is a single WAL record and off we go with > another checkpoint. If there hasn't been much WAL activity, there is > not much point in having another checkpoint record since there is > little if any time to be saved in recovery. > So why not avoid checkpoints until we have written at least 1 WAL file > worth of data? +1, but I think you need to compare to the last checkpoint's REDO pointer, not to the position of the checkpoint record itself. Otherwise, the argument falls down if there was a lot of activity during the last checkpoint (which is not unlikely in these days of spread checkpoints). Also I think the comment needs more extensive revision than you gave it. regards, tom lane