From: Bruce Momjian <bruce@momjian.us>
Date: Tue, 19 Oct 2010 15:49:53 +0000 (+0000)
Subject: Add mention of using tools/fsync to test fsync methods. Restructure
X-Git-Tag: REL8_4_6~31
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d94d0a8c83715cb403267f0c89068781b706ddff;p=postgresql

Add mention of using tools/fsync to test fsync methods. Restructure
recent wal_sync_method doc paragraph to be clearer.
---

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 76af829d2d..3aa74870f8 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1458,13 +1458,15 @@ 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 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">.
         This parameter can only be set in the <filename>postgresql.conf</>
         file or on the server command line.
        </para>
diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml
index 36545e4e1a..f3ee6bb7a7 100644
--- a/doc/src/sgml/wal.sgml
+++ b/doc/src/sgml/wal.sgml
@@ -482,11 +482,13 @@
   <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>