On 2020/05/28 8:43, Thomas Munro wrote:
On Wed, May 27, 2020 at 7:09 PM Simon Riggs <si...@2ndquadrant.com> wrote:
On Wed, 27 May 2020 at 04:27, Fujii Masao <masao.fu...@oss.nttdata.com> wrote:
Hi,
The group of wal_init_zero and wal_recycle is WAL_SETTINGS in guc.c,
but their descriptions are located in "19.6. Replication"/"19.6.1. Sending
Servers" section. This seems a documentation bug. They should be located
in "19.5. Write Ahead Log"/"19.5.1. Settings". Thought?
+1
Thanks! Patch attached.
Since they are located just before wal_buffers in postgresql.conf.sample,
I moved the descriptions of them also just before that of wal_buffers
in "Write Ahead Log"/"Settings" section.
BTW, while reading guc.c, I found the GUC context of wal_recycle is
PGC_SUSET. But isn't it better to set it to PGC_SIGHUP because wal_recycle
doesn't affect any backends? Basically checkpointer and startup process
use wal_recycle.
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index a2694e548a..862baae0c8 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2820,6 +2820,41 @@ include_dir 'conf.d'
</listitem>
</varlistentry>
+ <varlistentry id="guc-wal-init-zero" xreflabel="wal_init_zero">
+ <term><varname>wal_init_zero</varname> (<type>boolean</type>)
+ <indexterm>
+ <primary><varname>wal_init_zero</varname> configuration
parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ If set to <literal>on</literal> (the default), this option causes new
+ WAL files to be filled with zeroes. On some file systems, this ensures
+ that space is allocated before we need to write WAL records. However,
+ <firstterm>Copy-On-Write</firstterm> (COW) file systems may not benefit
+ from this technique, so the option is given to skip the unnecessary
+ work. If set to <literal>off</literal>, only the final byte is written
+ when the file is created so that it has the expected size.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry id="guc-wal-recycle" xreflabel="wal_recycle">
+ <term><varname>wal_recycle</varname> (<type>boolean</type>)
+ <indexterm>
+ <primary><varname>wal_recycle</varname> configuration
parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ If set to <literal>on</literal> (the default), this option causes WAL
+ files to be recycled by renaming them, avoiding the need to create new
+ ones. On COW file systems, it may be faster to create new ones, so the
+ option is given to disable this behavior.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="guc-wal-buffers" xreflabel="wal_buffers">
<term><varname>wal_buffers</varname> (<type>integer</type>)
<indexterm>
@@ -3752,41 +3787,6 @@ restore_command = 'copy "C:\\server\\archivedir\\%f"
"%p"' # Windows
</listitem>
</varlistentry>
- <varlistentry id="guc-wal-init-zero" xreflabel="wal_init_zero">
- <term><varname>wal_init_zero</varname> (<type>boolean</type>)
- <indexterm>
- <primary><varname>wal_init_zero</varname> configuration
parameter</primary>
- </indexterm>
- </term>
- <listitem>
- <para>
- If set to <literal>on</literal> (the default), this option causes new
- WAL files to be filled with zeroes. On some file systems, this ensures
- that space is allocated before we need to write WAL records. However,
- <firstterm>Copy-On-Write</firstterm> (COW) file systems may not benefit
- from this technique, so the option is given to skip the unnecessary
- work. If set to <literal>off</literal>, only the final byte is written
- when the file is created so that it has the expected size.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry id="guc-wal-recycle" xreflabel="wal_recycle">
- <term><varname>wal_recycle</varname> (<type>boolean</type>)
- <indexterm>
- <primary><varname>wal_recycle</varname> configuration
parameter</primary>
- </indexterm>
- </term>
- <listitem>
- <para>
- If set to <literal>on</literal> (the default), this option causes WAL
- files to be recycled by renaming them, avoiding the need to create new
- ones. On COW file systems, it may be faster to create new ones, so the
- option is given to disable this behavior.
- </para>
- </listitem>
- </varlistentry>
-
<varlistentry id="guc-max-slot-wal-keep-size"
xreflabel="max_slot_wal_keep_size">
<term><varname>max_slot_wal_keep_size</varname> (<type>integer</type>)
<indexterm>
