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Diffstat (limited to 'doc/src/sgml/wal.sgml')
| -rw-r--r-- | doc/src/sgml/wal.sgml | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index 2bb27a8468..6b3406b7de 100644 --- a/doc/src/sgml/wal.sgml +++ b/doc/src/sgml/wal.sgml @@ -803,6 +803,18 @@ counted as <literal>wal_write</literal> and <literal>wal_sync</literal> in <structname>pg_stat_wal</structname>, respectively. </para> + + <para> + The <xref linkend="guc-recovery-prefetch"/> parameter can be used to reduce + I/O wait times during recovery by instructing the kernel to initiate reads + of disk blocks that will soon be needed but are not currently in + <productname>PostgreSQL</productname>'s buffer pool. + The <xref linkend="guc-maintenance-io-concurrency"/> and + <xref linkend="guc-wal-decode-buffer-size"/> settings limit prefetching + concurrency and distance, respectively. By default, it is set to + <literal>try</literal>, which enabled the feature on systems where + <function>posix_fadvise</function> is available. + </para> </sect1> <sect1 id="wal-internals"> |