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<chapter id="backup">

<title>Backup and Restore</title>

<important>

<para>

When your database schema relies on OIDs (forinstances as foreign

When your database schema relies on OIDs (forinstance 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.

option. <quote>Large objects</> are not dumped by default, either.

See <application>pg_dump</>'s command reference page if you use

large objects.

</para>

</important>

users, then the dump will instruct <application>psql</> to connect

as each affected user in turn and then create the relevant

objects. This way the original ownership is preserved. This also

means, however, that all theseuser must already exist, and

means, however, that all theseusers must already exist, and

furthermore that you must be allowed to connect as each of them.

It might therefore be necessary to temporarily relax the client

authentication settings.

</para>

<para>

The ability of <application>pg_dump</> and <application>psql</> to

write or read from pipesalso make it possible to dump a database

directory from one server to another, for example

writetoor read from pipesmakes it possible to dump a database

directly from one server to another, for example

<informalexample>

<programlisting>

pg_dump -h <replaceable>host1</> <replaceable>dbname</> | psql -h <replaceable>host2</> <replaceable>dbname</>