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 87d182c4c45b9e8542ae6b4bfed1c9d3cc388089..f178835d2b0783f69a9f9218c3d9c69a9810ae86 100644 (file)
--- 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 5678d6ebdd87ffc2fe85e45f40ce6977c6c0d307..7b50bddd04c71069a2a128fd72dc4b59f4bc3dae 100644 (file)
--- 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.