=================
 Partial Backups
=================

|xtrabackup| supports taking partial backups when the :term:`innodb_file_per_table` option is enabled. There are two ways to create partial backups: matching the tables' names with a regular expression or providing a list of them in a file.

.. warning:: If any of the matched or listed tables is deleted during the backup, |xtrabackup| will fail.

For the purposes of this manual page, we will assume that there is a database named ``test`` which contains tables named ``t1`` and ``t2``.

Using the :option:`--tables` Option
===================================

The first method is with the :option:`--tables` option. The option's value is a regular expression that is matched against the fully qualified tablename, including the database name, in the form ``databasename.tablename``.

To back up only tables in the ``test`` database, you can use the following command: ::

  xtrabackup --backup --datadir=/var/lib/mysql --target-dir=/data/backups/ \
  --tables="^test[.].*"

To back up only the table ``test.t1``, you can use the following command: ::

  xtrabackup --backup --datadir=/var/lib/mysql --target-dir=/data/backups/ \
  --tables="^test[.]t1"

Using the :option:`--tables-file` Option
========================================

The ``--tables-file`` option specifies a file that can contain multiple table names, one table name per line in the file. Only the tables named in the file will be backed up. Names are matched exactly, case-sensitive, with no pattern or regular expression matching. The table names must be fully qualified, in ``databasename.tablename`` format. 

Preparing the Backup
====================

When you use the :option:`--prepare` option on a partial backup, you will see warnings about tables that don't exist. That is because these tables exist in the data dictionary inside InnoDB, but the corresponding :term:`.ibd` files don't exist. They were not copied into the backup directory. These tables will be removed from the data dictionary, and when you restore the backup and start InnoDB, they will no longer exist and will not cause any errors or warnings to be printed to the log file.

An example of the error message you will see during the prepare phase follows. ::

  InnoDB: Reading tablespace information from the .ibd files...
  101107 22:31:30  InnoDB: Error: table 'test1/t'
  InnoDB: in InnoDB data dictionary has tablespace id 6,
  InnoDB: but tablespace with that id or name does not exist. It will be removed from data dictionary.