On Sat, Jul 17, 2010 at 4:22 AM, Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> wrote: >> The patch adds the document about the relationship between a restartpoint >> and checkpoint_segments parameter. > > Thanks, committed with minor editorialization
Thanks.
> There will always be at least one WAL segment file, and will normally
> not be more than (2 + <varname>checkpoint_completion_target</varname>) *
> <varname>checkpoint_segments</varname> + 1
> + or <varname>checkpoint_segments</> + <xref
> linkend="guc-wal-keep-segments"> + 1
> files. Each segment file is normally 16 MB (though this size can be
> altered when building the server). You can use this to estimate space
> requirements for <acronym>WAL</acronym>.
Sorry, I was wrong here. The correct formula is:
(2 + checkpoint_completion_target) * checkpoint_segments +
wal_keep_segments + 1
The attached patch fixes this fault. And I attached the PDF file which
illustrates the proof of the formula.
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
num_of_wal_formula_v1.patch
Description: Binary data
20100721_num_of_wal_in_pg_xlog.pdf
Description: Adobe PDF document
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