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| -rw-r--r-- | doc/src/sgml/wal.sgml | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index 373aa961dc7..3b013746a31 100644 --- a/doc/src/sgml/wal.sgml +++ b/doc/src/sgml/wal.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/wal.sgml,v 1.53 2008/05/02 19:52:37 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/wal.sgml,v 1.54 2008/12/06 21:34:27 momjian Exp $ --> <chapter id="wal"> <title>Reliability and the Write-Ahead Log</title> @@ -135,6 +135,21 @@ roll-forward recovery, also known as REDO.) </para> + <tip> + <para> + Because <acronym>WAL</acronym> restores database file + contents after a crash, it is not necessary to use a + journaled filesystem; in fact, journaling overhead can + reduce performance. For best performance, turn off + <emphasis>data</emphasis> journaling as a filesystem mount + option, e.g. use <literal>data=writeback</> on Linux. + Meta-data journaling (e.g. file creation and directory + modification) is still desirable for faster rebooting after + a crash. + </para> + </tip> + + <para> Using <acronym>WAL</acronym> results in a significantly reduced number of disk writes, because only the log |