The cluster restoration program is implemented as a separate command-line utility ndb_restore, which can normally be found in the MySQL bin directory. This program reads the files created as a result of the backup and inserts the stored information into the database.

ndb_restore must be executed once for each of the backup files that were created by the START BACKUP command used to create the backup (see Section 17.5.3.2, “Using The MySQL Cluster Management Client to Create a Backup”). This is equal to the number of data nodes in the cluster at the time that the backup was created.

The following table includes options that are specific to the MySQL Cluster native backup restoration program ndb_restore. Additional descriptions follow the table. For options common to all MySQL Cluster programs, see Section 17.4.23, “Options Common to MySQL Cluster Programs”.

Typical options for this utility are shown here:

ndb_restore [-c connectstring] -n node_id [-m] -b backup_id \
    -r --backup_path=/path/to/backup/files

The -c option is used to specify a connectstring which tells ndb_restore where to locate the cluster management server. (See Section 17.3.2.3, “The MySQL Cluster Connectstring”, for information on connectstrings.) If this option is not used, then ndb_restore attempts to connect to a management server on localhost:1186. This utility acts as a cluster API node, and so requires a free connection “slot” to connect to the cluster management server. This means that there must be at least one [api] or [mysqld] section that can be used by it in the cluster config.ini file. It is a good idea to keep at least one empty [api] or [mysqld] section in config.ini that is not being used for a MySQL server or other application for this reason (see Section 17.3.2.7, “Defining SQL and Other API Nodes in a MySQL Cluster”).

You can verify that ndb_restore is connected to the cluster by using the SHOW command in the ndb_mgm management client. You can also accomplish this from a system shell, as shown here:

shell> ndb_mgm -e "SHOW"

-n is used to specify the node ID of the data node on which the backups were taken.

The first time you run the ndb_restore restoration program, you also need to restore the metadata. In other words, you must re-create the database tables — this can be done by running it with the -m option. Note that the cluster should have an empty database when starting to restore a backup. (In other words, you should start ndbd with --initial prior to performing the restore. You should also remove manually any Disk Data files present in the data node's DataDir.)

It is possible to restore data without restoring table metadata. Prior to MySQL 5.1.17, ndb_restore did not perform any checks of table schemas; if a table was altered between the time the backup was taken and when ndb_restore was run, ndb_restore would still attempt to restore the data to the altered table.

Beginning with MySQL 5.1.17, the default behavior is for ndb_restore to fail with an error if table data do not match the table schema; this can be overridden using the --skip-table-check or -s option. Prior to MySQL 5.1.21, if this option is used, then ndb_restore attempts to fit data into the existing table schema, but the result of restoring a backup to a table schema that does not match the original is unspecified.

Beginning with MySQL Cluster NDB 6.3.8, ndb_restore supports limited attribute promotion in much the same way that it is supported by MySQL replication; that is, data backed up from a column of a given type can generally be restored to a column using a “larger, similar” type. For example, data from a CHAR(20) column can be restored to a column declared as VARCHAR(20), VARCHAR(30), or CHAR(30); data from a MEDIUMINT column can be restored to a column of type INT or BIGINT. See Section 16.4.1.5.2, “Replication of Columns Having Different Data Types”, for a table of type conversions currently supported by attribute promotion.

Attribute promotion by ndb_restore must be enabled explicitly, as follows:

In addition to --promote-attributes, a --preserve-trailing-spaces option is also available for use with ndb_restore beginning with MySQL Cluster NDB 6.3.8. This option (short form -R) causes trailing spaces to be preserved when promoting a CHAR column to VARCHAR or a BINARY column to VARBINARY. Otherwise, any trailing spaces are dropped from column values when they are inserted into the new columns.

The -b option is used to specify the ID or sequence number of the backup, and is the same number shown by the management client in the Backup backup_id completed message displayed upon completion of a backup. (See Section 17.5.3.2, “Using The MySQL Cluster Management Client to Create a Backup”.)

--restore_epoch (short form: -e) adds (or restores) epoch information to the cluster replication status table. This is useful for starting replication on a MySQL Cluster replication slave. When this option is used, the row in the mysql.ndb_apply_status having 0 in the id column is updated if it already exists; such a row is inserted if it does not already exist. (See Section 17.6.9, “MySQL Cluster Backups With MySQL Cluster Replication”.)

The path to the backup directory is required; this is supplied to ndb_restore using the --backup_path option, and must include the subdirectory corresponding to the ID backup of the backup to be restored. For example, if the data node's DataDir is /var/lib/mysql-cluster, then the backup directory is /var/lib/mysql-cluster/BACKUP, and the backup files for the backup with the ID 3 can be found in /var/lib/mysql-cluster/BACKUP/BACKUP-3. The path may be absolute or relative to the directory in which the ndb_restore executable is located, and may be optionally prefixed with backup_path=.

[backup_path=]/path/to/backup/files

It is possible to restore a backup to a database with a different configuration than it was created from. For example, suppose that a backup with backup ID 12, created in a cluster with two database nodes having the node IDs 2 and 3, is to be restored to a cluster with four nodes. Then ndb_restore must be run twice — once for each database node in the cluster where the backup was taken. However, ndb_restore cannot always restore backups made from a cluster running one version of MySQL to a cluster running a different MySQL version. See Section 17.2.6.2, “MySQL Cluster 5.1 and MySQL Cluster NDB 6.x/7.x Upgrade and Downgrade Compatibility”, for more information.

For more rapid restoration, the data may be restored in parallel, provided that there is a sufficient number of cluster connections available. That is, when restoring to multiple nodes in parallel, you must have an [api] or [mysqld] section in the cluster config.ini file available for each concurrent ndb_restore process. However, the data files must always be applied before the logs.

Formerly, when using ndb_restore to restore a backup made from a MySQL 5.0 cluster to a 5.1 cluster, VARCHAR columns were not resized and were recreated using the 5.0 fixed format. Beginning with MySQL 5.1.19, ndb_restore recreates such VARCHAR columns using MySQL Cluster 5.1's variable-width format. Also beginning with MySQL 5.1.19, this behavior can be overridden using the --no-upgrade option (short form: -u) when running ndb_restore.

This option causes ndb_restore to print its output to stdout. Beginning with MySQL 5.1.18, several additional options are available for use with the --print_data option in generating data dumps, either to stdout, or to a file. These are similar to some of the options used with mysqldump, and are shown in the following list:

Beginning with MySQL 5.1.18, it is possible to restore selected databases, or to restore selected tables from a given database using the syntax shown here:

ndb_restore other_options db_name,[db_name[,...] | tbl_name[,tbl_name][,...]]

In other words, you can specify either of the following to be restored:

--include-databases=db_name[,db_name][,...]

--include-tables=db_name.tbl_name[,db_name.tbl_name][,...]

Beginning with MySQL Cluster NDB 6.3.22 and MySQL Cluster NDB 6.4.3, you can (and should) use instead the --include-databases option or the --include-tables option for restoring only specific databases or tables, respectively. --include-databases takes a comma-delimited list of databases to be restored. --include-tables takes a comma-delimited list of tables (in database.table format) to be restored.

When --include-databases or --include-tables is used, only those databases or tables named by the option are restored; all other databases and tables are excluded by ndb_restore, and are not restored.

The following table shows several invocations of ndb_restore using --include-* options (other options possibly required have been omitted for clarity), and the effects these have on restoring from a MySQL Cluster backup:

Beginning with MySQL Cluster NDB 6.3.29 and MySQL Cluster NDB 7.0.10, you can use these two options together. For example, the following causes all tables in databases db1 and db2, together with the tables t1 and t2 in database db3, to be restored (and no other databases or tables):

shell> ndb_restore [...] --include-databases=db1,db2 --include-tables=db3.t1,db3.t2

(Again we have omitted other, possibly required, options in the example just shown.)

--exclude-databases=db_name[,db_name][,...]

--exclude-tables=db_name.tbl_name[,db_name.tbl_name][,...]

Also beginning with MySQL Cluster NDB 6.3.22 and MySQL Cluster NDB 6.4.3, it is possible to exclude from being restored one or more databases or tables using the ndb_restore options --exclude-databases and --exclude-tables. --exclude-databases takes a comma-delimited list of one or more databases which should not be restored. --exclude-tables takes a comma-delimited list of one or more tables (using database.table format) which should not be restored.

When --exclude-databases or --exclude-tables is used, only those databases or tables named by the option are excluded; all other databases and tables are restored by ndb_restore.

This table shows several invocations of ndb_restore usng --exclude-* options (other options possibly required have been omitted for clarity), and the effects these options have on restoring from a MySQL Cluster backup:

Beginning with MySQL Cluster NDB 6.3.29 and MySQL Cluster NDB 7.0.10, you can use these two options together. For example, the following causes all tables in all databases except for databases db1 and db2, along with the tables t1 and t2 in database db3, not to be restored:

shell> ndb_restore [...] --exclude-databases=db1,db2 --exclude-tables=db3.t1,db3.t2

(Again, we have omitted other possibly necessary options in the interest of clarity and brevity from the example just shown.)

Beginning with MySQL Cluster NDB 6.3.29 and MySQL Cluster NDB 7.0.10, you can use --include-* and --exclude-* options together, subject to the following rules:

For example, the following set of options causes ndb_restore to restore all tables from database db1 except db1.t1, while restoring no other tables from any other databases:

          
--include-databases=db1 --exclude-tables=db1.t1

However, reversing the order of the options just given simply causes all tables from database db1 to be restored (including db1.t1, but no tables from any other database), because the --include-dabases option, being farthest to the right, is the first match against database db1 and thus takes precedence over any other option that matches db1 or any tables in db1:

          
--exclude-tables=db1.t1 --include-databases=db1

--exclude-missing-columns

Beginning with MySQL Cluster NDB 6.3.26 and MySQL Cluster NDB 7.0.7, it is also possible to restore only selected table columns using the --exclude-missing-columns option. When this option is used, ndb_restore ignores any columns missing from tables being restored as compared to the versions of those tables found in the backup. This option applies to all tables being restored. If you wish to apply this option only to selected tables or databases, you can use it in combination with one or more of the options described in the previous paragraph to do so, then restore data to the remaining tables using a complementary set of these options.

--disable-indexes

Beginning with MySQL Cluster NDB 6.3.31, MySQL Cluster NDB 7.0.11, and MySQL CLuster NDB 7.1.2, you can use this option with ndb_restore to disable the indexes found in a backup for faster restoration of the data.

--rebuild-indexes

Beginning with MySQL Cluster NDB 6.3.31, MySQL Cluster NDB 7.0.11, and MySQL CLuster NDB 7.1.2, you can use this option with ndb_restore to cause multi-threaded rebuilding of the ordered indexes found in a backup during the restoration process.

Error reporting.  ndb_restore reports both temporary and permanent errors. In the case of temporary errors, it may able to recover from them. Beginning with MySQL 5.1.12, it reports Restore successful, but encountered temporary error, please look at configuration in such cases.