From 6f609199df2c8d38ed0391180a2ff467333ae57c Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Tue, 19 Oct 2010 14:58:03 +0000 Subject: [PATCH] Add mention of using tools/fsync to test fsync methods. Restructure recent wal_sync_method doc paragraph to be clearer. --- doc/src/sgml/config.sgml | 12 ++++++------ doc/src/sgml/wal.sgml | 12 +++++++----- 2 files changed, 13 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index b904238800a..65ac6fc5d2d 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -1569,13 +1569,13 @@ SET ENABLE_SEQSCAN TO OFF; Not all of these choices are available on all platforms. - The default is the first method in the above list that is supported - by the platform. The default is not necessarily best; it may be - necessary to change this setting, or other aspects of your system - configuration, in order to create a crash-safe configuration, as - discussed in , or to achieve best - performance. The open_* options also use O_DIRECT if available. + The default is the first method in the above list that is supported + by the platform. The default is not necessarily ideal; it might be + necessary to change this setting or other aspects of your system + configuration in order to create a crash-safe configuration or + achieve optimal performance. + These aspects are discussed in . The utility src/tools/fsync in the PostgreSQL source tree can do performance testing of various fsync methods. This parameter can only be set in the postgresql.conf diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index 757c884c87c..8d8504552d2 100644 --- a/doc/src/sgml/wal.sgml +++ b/doc/src/sgml/wal.sgml @@ -530,11 +530,13 @@ The parameter determines how PostgreSQL will ask the kernel to force - WAL updates out to disk. - With the exception of fsync_writethrough, which can sometimes - force a flush of the disk cache even when other options do not do so, - all the options should be the same in terms of reliability. - However, it's quite platform-specific which one will be the fastest. + WAL updates out to disk. + All the options should be the same in terms of reliability, with + the exception of fsync_writethrough, which can sometimes + force a flush of the disk cache even when other options do not do so. + However, it's quite platform-specific which one will be the fastest; + you can test option speeds using the utility src/tools/fsync + in the PostgreSQL source tree. Note that this parameter is irrelevant if fsync has been turned off. -- 2.47.2