Re: archive_timeout behavior for no activity

Fujii Masao wrote:
> On Fri, Jan 15, 2010 at 12:50 AM, Bruce Momjian <bruce@momjian.us> wrote:
> > Looking at the archive_timeout documentation and CheckArchiveTimeout(),
> > it appears we force a new xlog file and archive it even if no activity
> > has been recorded in the xlog file. ?Is this correct?
> 
> No. CheckArchiveTimeout() doesn't switch WAL files if there is no activity
> after the last switch. In fact, though it calls RequestXLogSwitch(),
> the switch is skipped in XLogInsert() because we are exactly at the start
> of a file in that case.
> 
> But unfortunately checkpoint would be often recorded between each
> switches. So the archive_timeout appears to always force a new WAL file.

I have documented that increasing checkpoint_timeout can avoid WAL
writes on idle systems with archive_timeout.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +