diff options
| -rw-r--r-- | doc/src/sgml/config.sgml | 12 | ||||
| -rw-r--r-- | 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; </itemizedlist> <para> 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 <xref linkend="wal-reliability">, or to achieve best - performance. The <literal>open_</>* options also use <literal>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 <xref linkend="wal-reliability">. The utility <filename>src/tools/fsync</> in the PostgreSQL source tree can do performance testing of various fsync methods. This parameter can only be set in the <filename>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 @@ <para> The <xref linkend="guc-wal-sync-method"> parameter determines how <productname>PostgreSQL</productname> will ask the kernel to force - <acronym>WAL</acronym> updates out to disk. - With the exception of <literal>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. + <acronym>WAL</acronym> updates out to disk. + All the options should be the same in terms of reliability, with + the exception of <literal>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 <filename>src/tools/fsync</> + in the PostgreSQL source tree. Note that this parameter is irrelevant if <varname>fsync</varname> has been turned off. </para> |