From cf9f6c8d8e9df28f3fbe1850ca7f042b2c01252e Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 2 May 2008 19:52:37 +0000
Subject: Extend yesterday's patch making BLCKSZ and RELSEG_SIZE configurable
 to also let XLOG_BLCKSZ and XLOG_SEG_SIZE be set via configure.  Per a
 proposal by Mark Wong, though I thought it better to call the switches after
 "wal" rather than "xlog".

---
 doc/src/sgml/installation.sgml | 30 +++++++++++++++++++++++++++++-
 doc/src/sgml/wal.sgml          |  9 ++++++---
 2 files changed, 35 insertions(+), 4 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/installation.sgml b/doc/src/sgml/installation.sgml
index d0933bf7d19..e6de85f8c77 100644
--- a/doc/src/sgml/installation.sgml
+++ b/doc/src/sgml/installation.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/installation.sgml,v 1.308 2008/05/02 01:08:26 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/installation.sgml,v 1.309 2008/05/02 19:52:37 tgl Exp $ -->
 
 <chapter id="installation">
  <title><![%standalone-include[<productname>PostgreSQL</>]]>
@@ -1103,6 +1103,34 @@ su - postgres
        </listitem>
       </varlistentry>
 
+      <varlistentry>
+       <term><option>--with-wal-segsize=<replaceable>SEGSIZE</replaceable></option></term>
+       <listitem>
+        <para>
+         Set the <firstterm>WAL segment size</>, in megabytes.  This is
+         the size of each individual file in the WAL log.  It may be useful
+         to adjust this size to control the granularity of WAL log shipping.
+         The default size is 16 megabytes.
+         The value must be a power of 2 between 1 and 64 (megabytes).
+         Note that changing this value requires an initdb.
+        </para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
+       <term><option>--with-wal-blocksize=<replaceable>BLOCKSIZE</replaceable></option></term>
+       <listitem>
+        <para>
+         Set the <firstterm>WAL block size</>, in kilobytes.  This is the unit
+         of storage and I/O within the WAL log.  The default, 8 kilobytes,
+         is suitable for most situations; but other values may be useful
+         in special cases.
+         The value must be a power of 2 between 1 and 64 (kilobytes).
+         Note that changing this value requires an initdb.
+        </para>
+       </listitem>
+      </varlistentry>
+
       <varlistentry>
        <term><option>--disable-spinlocks</option></term>
        <listitem>
diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml
index 090a133185f..373aa961dc7 100644
--- a/doc/src/sgml/wal.sgml
+++ b/doc/src/sgml/wal.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/wal.sgml,v 1.52 2007/12/29 17:55:07 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/wal.sgml,v 1.53 2008/05/02 19:52:37 tgl Exp $ -->
 
 <chapter id="wal">
  <title>Reliability and the Write-Ahead Log</title>
@@ -487,8 +487,11 @@
   <para>
    <acronym>WAL</acronym> logs are stored in the directory
    <filename>pg_xlog</filename> under the data directory, as a set of
-   segment files, normally each 16 MB in size.  Each segment is divided into
-   pages, normally 8 kB each.  The log record headers are described in
+   segment files, normally each 16 MB in size (but the size can be changed
+   by altering the <option>--with-wal-segsize</> configure option when
+   building the server).  Each segment is divided into pages, normally
+   8 kB each (this size can be changed via the <option>--with-wal-blocksize</>
+   configure option).  The log record headers are described in
    <filename>access/xlog.h</filename>; the record content is dependent
    on the type of event that is being logged.  Segment files are given
    ever-increasing numbers as names, starting at
-- 
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