From 43342891861cc2d08dea2b1c8b190e15e5a36551 Mon Sep 17 00:00:00 2001 From: Simon Riggs Date: Thu, 3 Nov 2011 08:52:20 +0000 Subject: [PATCH] Improve docs for timing and skipping of checkpoints Greg Smith --- doc/src/sgml/wal.sgml | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index ff825eca3b..3b86a4e111 100644 --- a/doc/src/sgml/wal.sgml +++ b/doc/src/sgml/wal.sgml @@ -424,8 +424,15 @@ linkend="guc-checkpoint-segments"> log segments, or every seconds, whichever comes first. The default settings are 3 segments and 300 seconds (5 minutes), respectively. - It is also possible to force a checkpoint by using the SQL command - CHECKPOINT. + In cases where there are little or no writes to the WAL, checkpoints will be + skipped even if checkpoint_timeout has passed. At least one new WAL segment + must have been created before an automatic checkpoint occurs. The time + between checkpoints and when new WAL segments are created are not related + in any other way. If file-based WAL shipping is being used and you want to + bound how often files are sent to standby server, to reduce potential data + loss you should adjust archive_timeout parameter rather than the checkpoint + parameters. It is also possible to force a checkpoint by using the SQL + command CHECKPOINT. -- 2.40.0