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Document how to use psql's --single-transaction option to rollback restoring

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an SQL dump if an error occurs. Along the way, make some improvements and
copy-edits to the surrounding text. Patch from Simon Riggs, additional
fixes by Neil Conway.
This commit is contained in:
Neil Conway 2006-09-19 19:04:51 +00:00
parent 85fca79a02
commit f7ea4eeed6
1 changed files with 39 additions and 22 deletions
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61
doc/src/sgml/backup.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.87 2006/09/19 15:18:41 neilc Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.88 2006/09/19 19:04:51 neilc Exp $ -->
<chapter id="backup">
<title>Backup and Restore</title>
@ -84,7 +84,7 @@ pg_dump <replaceable class="parameter">dbname</replaceable> &gt; <replaceable cl
<important>
<para>
When your database schema relies on OIDs (for instance as foreign
If your database schema relies on OIDs (for instance as foreign
keys) you must instruct <application>pg_dump</> to dump the OIDs
as well. To do this, use the <option>-o</option> command line
option.
@ -105,30 +105,42 @@ psql <replaceable class="parameter">dbname</replaceable> &lt; <replaceable class
you used as <replaceable class="parameter">outfile</replaceable>
for the <application>pg_dump</> command. The database <replaceable
class="parameter">dbname</replaceable> will not be created by this
command, you must create it yourself from <literal>template0</> before executing
<application>psql</> (e.g., with <literal>createdb -T template0
<replaceable class="parameter">dbname</></literal>).
<application>psql</> supports options similar to <application>pg_dump</>
for controlling the database server location and the user name. See
<xref linkend="app-psql">'s reference page for more information.
command, so you must create it yourself from <literal>template0</>
before executing <application>psql</> (e.g., with
<literal>createdb -T template0 <replaceable
class="parameter">dbname</></literal>). <application>psql</>
supports similar options to <application>pg_dump</> for specifying
the database server to connect to and the user name to use. See
the <xref linkend="app-psql"> reference page for more information.
</para>
<para>
Not only must the target database already exist before starting to
run the restore, but so must all the users who own objects in the
dumped database or were granted permissions on the objects. If they
do not, then the restore will fail to recreate the objects with the
original ownership and/or permissions. (Sometimes this is what you want,
but usually it is not.)
Before restoring a SQL dump, all the users who own objects or were
granted permissions on objects in the dumped database must already
exist. If they do not, then the restore will fail to recreate the
objects with the original ownership and/or permissions.
(Sometimes this is what you want, but usually it is not.)
</para>
<para>
Once restored, it is wise to run <xref linkend="sql-analyze"
endterm="sql-analyze-title"> on each database so the optimizer has
useful statistics. An easy way to do this is to run
<command>vacuumdb -a -z</> to
<command>VACUUM ANALYZE</> all databases; this is equivalent to
running <command>VACUUM ANALYZE</command> manually.
By default, the <application>psql</> script will continue to
execute after an SQL error is encountered. You may wish to use the
following command at the top of the script to alter that
behaviour and have <application>psql</application> exit with an
exit status of 3 if an SQL error occurs:
<programlisting>
\set ON_ERROR_STOP
</programlisting>
Either way, you will only have a partially restored
dump. Alternatively, you can specify that the whole dump should be
restored as a single transaction, so the restore is either fully
completed or fully rolled back. This mode can be specified by
passing the <option>-1</> or <option>--single-transaction</>
command-line options to <application>psql</>. When using this
mode, be aware that even the smallest of errors can rollback a
restore that has already run for many hours. However, that may
still be preferable to manually cleaning up a complex database
after a partially restored dump.
</para>
<para>
@ -153,8 +165,13 @@ pg_dump -h <replaceable>host1</> <replaceable>dbname</> | psql -h <replaceable>h
</important>
<para>
For advice on how to load large amounts of data into
<productname>PostgreSQL</productname> efficiently, refer to <xref
After restoring a backup, it is wise to run <xref
linkend="sql-analyze" endterm="sql-analyze-title"> on each
database so the query optimizer has useful statistics. An easy way
to do this is to run <command>vacuumdb -a -z</>; this is
equivalent to running <command>VACUUM ANALYZE</> on each database
manually. For more advice on how to load large amounts of data
into <productname>PostgreSQL</> efficiently, refer to <xref
linkend="populate">.
</para>
</sect2>