Author: paul
Date: 2008-07-23 19:26:52 +0200 (Wed, 23 Jul 2008)
New Revision: 11329
Log:
r32898@frost: paul | 2008-07-23 12:19:48 -0500
Additional information about compression for BACKUP DATABASE
Modified:
trunk/refman-6.0/sql-syntax-server-administration.xml
Property changes on: trunk
___________________________________________________________________
Name: svk:merge
- 4767c598-dc10-0410-bea0-d01b485662eb:/mysqldoc-local/mysqldoc/trunk:35828
7d8d2c4e-af1d-0410-ab9f-b038ce55645b:/mysqldoc-local/mysqldoc:32880
b5ec3a16-e900-0410-9ad2-d183a3acac99:/mysqldoc-local/mysqldoc/trunk:14218
bf112a9c-6c03-0410-a055-ad865cd57414:/mysqldoc-local/mysqldoc/trunk:32403
+ 4767c598-dc10-0410-bea0-d01b485662eb:/mysqldoc-local/mysqldoc/trunk:35828
7d8d2c4e-af1d-0410-ab9f-b038ce55645b:/mysqldoc-local/mysqldoc:32898
b5ec3a16-e900-0410-9ad2-d183a3acac99:/mysqldoc-local/mysqldoc/trunk:14218
bf112a9c-6c03-0410-a055-ad865cd57414:/mysqldoc-local/mysqldoc/trunk:32403
Modified: trunk/refman-6.0/sql-syntax-server-administration.xml
===================================================================
--- trunk/refman-6.0/sql-syntax-server-administration.xml 2008-07-23 16:02:22 UTC (rev 11328)
+++ trunk/refman-6.0/sql-syntax-server-administration.xml 2008-07-23 17:26:52 UTC (rev 11329)
Changed blocks: 5, Lines Added: 78, Lines Deleted: 31; 6981 bytes
@@ -2657,7 +2657,8 @@
BACKUP {DATABASE | SCHEMA}
{ * | <replaceable>db_name</replaceable> [, <replaceable>db_name</replaceable>] ... }
TO '<replaceable>image_file_name</replaceable>';
- [WITH COMPRESSION [COMPRESSION_ALGORITHM [=] <replaceable>algorithm_name</replaceable>]]
+ [WITH COMPRESSION
+ [COMPRESSION_ALGORITHM [=] <replaceable>algorithm_name</replaceable>]]
</programlisting>
<remark role="todo">
@@ -2701,24 +2702,44 @@
</para>
<para>
- As of MySQL 6.0.7, you can use the <literal>WITH
- COMPRESSION</literal> clause. This causes <literal>BACKUP
- DATABASE</literal> to compress the backup, which reduces the
- image size, and may also result in improved backup time by
- reducing writes to disk. The optional <literal>COMPRESSION
- ALGORITHM</literal> clause may be given when using <literal>WITH
- COMPRESSION</literal>. The only allowable algorithm name is
- <literal>gzip</literal>, which is also the default.
- <literal>gzip</literal> compression is the same as that done by
- the <command>gzip</command> command-line utility.
+ Upon successful completion, the <literal>BACKUP
+ DATABASE</literal> statement returns a result set with the
+ backup number. Warnings produced during the operation can be
+ displayed with <literal>SHOW WARNINGS</literal>. If the backup
+ operation fails, it returns an error and any file created by the
+ operation is deleted.
</para>
+<programlisting>
+mysql> <userinput>BACKUP DATABASE test TO '/tmp/world.backup';</userinput>
++-----------+
+| backup_id |
++-----------+
+| 8 |
++-----------+
+</programlisting>
+
<para>
- <literal>RESTORE</literal> detects whether a backup image has
- been compressed and uncompresses it automatically as necessary.
+ While the operation is in progress, it can be monitored as
+ described in
+ <xref linkend="backup-database-restore-monitoring"/>.
</para>
<para>
+ As of MySQL 6.0.7, you can use the <literal>WITH
+ COMPRESSION</literal> clause to cause <literal>BACKUP
+ DATABASE</literal> to compress the backup. This reduces the
+ image size. The optional
+ <literal>COMPRESSION_ALGORITHM</literal> clause may be given
+ when using <literal>WITH COMPRESSION</literal>. The only
+ allowable algorithm name is <literal>gzip</literal>, which is
+ also the default. <literal>gzip</literal> compression is the
+ same as that done by the <command>gzip</command> command-line
+ utility; it follows the conventions described as
+ <ulink url="http://www.faqs.org/rfcs/rfc1952.html"/>.
+ </para>
+
+ <para>
If <literal>WITH COMPRESSION</literal> is given, the entire
backup is compressed. It is not possible to selectively compress
some databases but not others within a single backup operation.
@@ -2734,30 +2755,45 @@
</para>
<para>
- Upon successful completion, the <literal>BACKUP
- DATABASE</literal> statement returns a result set with the
- backup number. Warnings produced during the operation can be
- displayed with <literal>SHOW WARNINGS</literal>. If the backup
- operation fails, it returns an error and any file created by the
- operation is deleted.
+ <literal>RESTORE</literal> detects whether a backup image is
+ compressed and uncompresses it automatically as necessary.
</para>
-<programlisting>
-mysql> <userinput>BACKUP DATABASE test TO '/tmp/world.backup';</userinput>
-+-----------+
-| backup_id |
-+-----------+
-| 8 |
-+-----------+
-</programlisting>
+ <para>
+ It is possible to manually compress and uncompressed image or
+ uncompress a compressed image by using a
+ <command>gzip</command>-compatible tool. In either case,
+ <literal>RESTORE</literal> will detect whether the image needs
+ to be compressed.
+ </para>
<para>
- While the operation is in progress, it can be monitored as
- described in
- <xref linkend="backup-database-restore-monitoring"/>.
+ For a MySQL server to be able to produce compressed images, it
+ must be compiled with <literal>zlib</literal> support (see
+ <xref linkend="configure-options"/>). If <literal>WITH
+ COMPRESSION</literal> is specified and <literal>zlib</literal>
+ support is not present, <literal>BACKUP DATABASE</literal> fails
+ with an error.
</para>
<para>
+ If you produce a compressed image with a server that has
+ <literal>zlib</literal> support, the image cannot be restored by
+ another server unless that server also has
+ <literal>zlib</literal> support, or unless you manually
+ uncompress the image first. Otherwise, the
+ <literal>RESTORE</literal> operation will fail with an error.
+ </para>
+
+ <para>
+ Use of compression may make backup and restore operations faster
+ by reducing the amount of disk I/O. There is some tradeoff due
+ to the increased CPU load required for compression and
+ uncompression calculations, but in general we expect this to be
+ outweighed by the time savings from reduced I/O.
+ </para>
+
+ <para>
<literal>BACKUP DATABASE</literal> backs up database and table
definitions, table data, stored routines, triggers, events, and
views. <literal>TEMPORARY</literal> tables are not included.
@@ -2776,7 +2812,10 @@
database selector syntax. Do not include them in the list of
names if you specify database names explicitly. To back up the
<literal>mysql</literal> database, you can use the
- <command>mysqldump</command> program.
+ <command>mysqldump</command> program. For an example backup
+ strategy that combines <literal>BACKUP DATABASE</literal> with
+ <command>mysqldump</command>, see
+ <xref linkend="backup-database-restore-quick-guide"/>.
</para>
<remark role="help-description-end"/>
@@ -2868,6 +2907,14 @@
<xref linkend="backup-database-restore-monitoring"/>.
</para>
+ <para>
+ <literal>RESTORE</literal> detects whether the image file is
+ compressed and uncompresses it automatically as necessary.
+ (Compressed image files can be produced by using the
+ <literal>WITH COMPRESSION</literal> clause in the
+ <literal>BACKUP DATABASE</literal> statement.)
+ </para>
+
<caution>
<para>
<literal>RESTORE</literal> is a destructive operation. Each
| Thread |
|---|
| • svn commit - mysqldoc@docsrva: r11329 - in trunk: . refman-6.0 | paul.dubois | 23 Jul |
