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From: Fujii Masao on 20 Jul 2010 23:25 On Sat, Jul 17, 2010 at 4:22 AM, Heikki Linnakangas <heikki.linnakangas(a)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 |