NDB_RESTORE(1)

NAME
ndb_restore - restore an NDB Cluster backup

SYNOPSIS

ndb_restore options

DESCRIPTION

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 21.5.3.2, “Using The NDB 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.

    Note

    Before using ndb_restore, it is recommended that the cluster be running in single user mode, unless you are restoring multiple data nodes in parallel. See Section 21.5.8, “NDB Cluster Single User Mode”, for more information.

The following table includes options that are specific to the NDB Cluster native backup restoration program ndb_restore. Additional descriptions follow the table. For options common to most NDB Cluster programs (including ndb_restore), see Options Common to NDB Cluster Programs(1).

Table 21.102. This table describes command-line options for the ndb_restore program

Typical options for this utility are shown here:

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

Normally, when restoring from an NDB Cluster backup, ndb_restore requires at a minimum the --nodeid (short form: -n), --backupid (short form: -b), and --backup_path options. In addition, when ndb_restore is used to restore any tables containing unique indexes, you must include --disable-indexes or --rebuild-indexes. (Bug #57782, Bug #11764893)

The -c option is used to specify a connection string which tells ndb_restore where to locate the cluster management server (see Section 21.3.3.3, “NDB Cluster Connection Strings”). 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 21.3.3.7, “Defining SQL and Other API Nodes in an NDB 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"

More detailed information about all options used by ndb_restore can be found in the following list:

    • --append
    Command-Line Format | --append

    When used with the --tab and --print_data options, this causes the data to be appended to any existing files having the same names.

    • --backup_path=dir_name
    Command-Line Format | --backup-path=dir_name
    Permitted Values | Type | directory name
     | Default | ./

    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=.

    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 21.2.8, “Upgrading and Downgrading NDB Cluster”, for more information.

        Important
        It is not possible to restore a backup made from a newer version of NDB Cluster using an older version of ndb_restore. You can restore a backup made from a newer version of MySQL to an older cluster, but you must use a copy of ndb_restore from the newer NDB Cluster version to do so.

        For example, to restore a cluster backup taken from a cluster running NDB Cluster 7.5.8 to a cluster running NDB Cluster 7.4.17, you must use the ndb_restore that comes with the NDB Cluster 7.5.8 distribution.

    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.

    • --backupid=#, -b
    Command-Line Format | --backupid=#
    Permitted Values | Type | numeric
     | Default | none

    This 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 21.5.3.2, “Using The NDB Cluster Management Client to Create a Backup”.)

        Important
        When restoring cluster backups, you must be sure to restore all data nodes from backups having the same backup ID. Using files from different backups will at best result in restoring the cluster to an inconsistent state, and may fail altogether.

    • --connect, -c
    Command-Line Format | --connect
    Permitted Values | Type | string
     | Default | localhost:1186

    Alias for --ndb-connectstring.

    • --disable-indexes
    Command-Line Format | --disable-indexes

    Disable restoration of indexes during restoration of the data from a native NDB backup. Afterwards, you can restore indexes for all tables at once with multi-threaded building of indexes using --rebuild-indexes, which should be faster than rebuilding indexes concurrently for very large tables.

    • --dont_ignore_systab_0, -f
    Command-Line Format | --dont-ignore-systab-0

    Normally, when restoring table data and metadata, ndb_restore ignores the copy of the NDB system table that is present in the backup. --dont_ignore_systab_0 causes the system table to be restored. This option is intended for experimental and development use only, and is not recommended in a production environment.

    • --exclude-databases=db-list
    Command-Line Format | --exclude-databases=db-list
    Permitted Values | Type | string
     | Default |

    Comma-delimited list of one or more databases which should not be restored.

    This option is often used in combination with --exclude-tables; see that option's description for further information and examples.

    • --exclude-intermediate-sql-tables[=TRUE|FALSE]
    Command-Line Format | --exclude-intermediate-sql-tables[=TRUE|FALSE]
    Permitted Values | Type | boolean
     | Default | TRUE

    When performing copying ALTER TABLE operations, mysqld creates intermediate tables (whose names are prefixed with #sql-). When TRUE, the --exclude-intermediate-sql-tables option keeps ndb_restore from restoring such tables that may have been left over from these operations. This option is TRUE by default.

    • --exclude-missing-columns
    Command-Line Format | --exclude-missing-columns

    It is possible to restore only selected table columns using this option, which causes ndb_restore to ignore 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 --include-* or --exclude-* options described elsewhere in this section to do so, then restore data to the remaining tables using a complementary set of these options.

    • --exclude-missing-tables
    Command-Line Format | --exclude-missing-tables

    It is possible to restore only selected tables using this option, which causes ndb_restore to ignore any tables from the backup that are not found in the target database.

    • --exclude-tables=table-list
    Command-Line Format | --exclude-tables=table-list
    Permitted Values | Type | string
     | Default |

    List of one or more tables to exclude; each table reference must include the database name. Often used together with --exclude-databases.

    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 an NDB Cluster backup:
    Option Used | Result
    --exclude-databases=db1 | All tables in all databases except db1 are restored; no tables in db1 are restored
    --exclude-databases=db1,db2 (or --exclude-databases=db1 --exclude-databases=db2) | All tables in all databases except db1 and db2 are restored; no tables in db1 or db2 are restored
    --exclude-tables=db1.t1 | All tables except t1 in database db1 are restored; all other tables in db1 are restored; all tables in all other databases are restored
    --exclude-tables=db1.t2,db2.t1 (or --exclude-tables=db1.t2 --exclude-tables=db2.t1) | All tables in database db1 except for t2 and all tables in database db2 except for table t1 are restored; no other tables in db1 or db2 are restored; all tables in all other databases are restored

    You can use these two options together. For example, the following causes all tables in all databases except for databases db1 and db2, and tables t1 and t2 in database db3, 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.)

    You can use --include-* and --exclude-* options together, subject to the following rules:

        • The actions of all --include-* and --exclude-* options are cumulative.

        • All --include-* and --exclude-* options are evaluated in the order passed to ndb_restore, from right to left.

        • In the event of conflicting options, the first (rightmost) option takes precedence. In other words, the first option (going from right to left) that matches against a given database or table “wins”.

    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-databases 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

    • --fields-enclosed-by=char
    Command-Line Format | --fields-enclosed-by=char
    Permitted Values | Type | string
     | Default |

    Each column value is enclosed by the string passed to this option (regardless of data type; see the description of --fields-optionally-enclosed-by).

    • --fields-optionally-enclosed-by
    Command-Line Format | --fields-optionally-enclosed-by
    Permitted Values | Type | string
     | Default |

    The string passed to this option is used to enclose column values containing character data (such as CHAR, VARCHAR, BINARY, TEXT, or ENUM).

    • --fields-terminated-by=char
    Command-Line Format | --fields-terminated-by=char
    Permitted Values | Type | string
     | Default | \t (tab)

    The string passed to this option is used to separate column values. The default value is a tab character (\t).

    • --hex
    Command-Line Format | --hex

    If this option is used, all binary values are output in hexadecimal format.

    • --include-databases=db-list
    Command-Line Format | --include-databases=db-list
    Permitted Values | Type | string
     | Default |

    Comma-delimited list of one or more databases to restore. Often used together with --include-tables; see the description of that option for further information and examples.

    • --include-tables=table-list
    Command-Line Format | --include-tables=table-list
    Permitted Values | Type | string
     | Default |

    Comma-delimited list of tables to restore; each table reference must include the database name.

    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 an NDB Cluster backup:
    Option Used | Result
    --include-databases=db1 | Only tables in database db1 are restored; all tables in all other databases are ignored
    --include-databases=db1,db2 (or --include-databases=db1 --include-databases=db2) | Only tables in databases db1 and db2 are restored; all tables in all other databases are ignored
    --include-tables=db1.t1 | Only table t1 in database db1 is restored; no other tables in db1 or in any other database are restored
    --include-tables=db1.t2,db2.t1 (or --include-tables=db1.t2 --include-tables=db2.t1) | Only the table t2 in database db1 and the table t1 in database db2 are restored; no other tables in db1, db2, or any other database are restored

    You can also 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.)

    It also possible to restore only selected databases, or selected tables from a single database, without any --include-* (or --exclude-*) options, 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:

        • All tables from one or more databases

        • One or more tables from a single database

    • --lines-terminated-by=char
    Command-Line Format | --lines-terminated-by=char
    Permitted Values | Type | string
     | Default | \n (linebreak)

    Specifies the string used to end each line of output. The default is a linefeed character (\n).

    • --lossy-conversions, -L
    Command-Line Format | --lossy-conversions
    Permitted Values | Type | boolean
     | Default | FALSE

    This option is intended to complement the --promote-attributes option. Using --lossy-conversions allows lossy conversions of column values (type demotions or changes in sign) when restoring data from backup. With some exceptions, the rules governing demotion are the same as for MySQL replication; see Section 16.4.1.10.2, “Replication of Columns Having Different Data Types”, for information about specific type conversions currently supported by attribute demotion.

    ndb_restore reports any truncation of data that it performs during lossy conversions once per attribute and column.

    • --no-binlog
    Command-Line Format | --no-binlog

    This option prevents any connected SQL nodes from writing data restored by ndb_restore to their binary logs.

    • --no-restore-disk-objects, -d
    Command-Line Format | --no-restore-disk-objects
    Permitted Values | Type | boolean
     | Default | FALSE

    This option stops ndb_restore from restoring any NDB Cluster Disk Data objects, such as tablespaces and log file groups; see Section 21.5.13, “NDB Cluster Disk Data Tables”, for more information about these.

    • --no-upgrade, -u
    Command-Line Format | --no-upgrade

    When using ndb_restore to restore a backup, VARCHAR columns created using the old fixed format are resized and recreated using the variable-width format now employed. This behavior can be overridden by specifying --no-upgrade.

    • --ndb-nodegroup-map=map, -z
    Command-Line Format | --ndb-nodegroup-map=map

    This option can be used to restore a backup taken from one node group to a different node group. Its argument is a list of the form source_node_group, target_node_group.

    • --nodeid=#, -n
    Command-Line Format | --nodeid=#
    Permitted Values | Type | numeric
     | Default | none

    Specify the node ID of the data node on which the backup was taken.

    When restoring to a cluster with different number of data nodes from that where the backup was taken, this information helps identify the correct set or sets of files to be restored to a given node. (In such cases, multiple files usually need to be restored to a single data node.) See the section called “Restoring to a different number of data nodes”, for additional information and examples.

    • --parallelism=#, -p
    Command-Line Format | --parallelism=#
    Permitted Values | Type | numeric
     | Default | 128
     | Min Value | 1
     | Max Value | 1024

    ndb_restore uses single-row transactions to apply many rows concurrently. This parameter determines the number of parallel transactions (concurrent rows) that an instance of ndb_restore tries to use. By default, this is 128; the minimum is 1, and the maximum is 1024.

    The work of performing the inserts is parallelized across the threads in the data nodes involved. This mechanism is employed for restoring bulk data from the .Data file—that is, the fuzzy snapshot of the data; it is not used for building or rebuilding indexes. The change log is applied serially; index drops and builds are DDL operations and handled separately. There is no thread-level parallelism on the client side of the restore.

    • --preserve-trailing-spaces, -P
    Command-Line Format | --preserve-trailing-spaces

    Cause trailing spaces to be preserved when promoting a fixed-width character data type to its variable-width equivalent—that is, when promoting a CHAR column value to VARCHAR, or a BINARY column value to VARBINARY. Otherwise, any trailing spaces are dropped from such column values when they are inserted into the new columns.

        Note
        Although you can promote CHAR columns to VARCHAR and BINARY columns to VARBINARY, you cannot promote VARCHAR columns to CHAR or VARBINARY columns to BINARY.

    • --print
    Command-Line Format | --print
    Permitted Values | Type | boolean
     | Default | FALSE

    Causes ndb_restore to print all data, metadata, and logs to stdout. Equivalent to using the --print_data, --print_meta, and --print_log options together.

        Note
        Use of --print or any of the --print_* options is in effect performing a dry run. Including one or more of these options causes any output to be redirected to stdout; in such cases, ndb_restore makes no attempt to restore data or metadata to an NDB Cluster.

    • --print_data
    Command-Line Format | --print-data
    Permitted Values | Type | boolean
     | Default | FALSE

    Cause ndb_restore to direct its output to stdout. Often used together with one or more of --tab, --fields-enclosed-by, --fields-optionally-enclosed-by, --fields-terminated-by, --hex, and --append.

    TEXT and BLOB column values are always truncated. Such values are truncated to the first 256 bytes in the output. This cannot currently be overridden when using --print_data.

    • --print_log
    Command-Line Format | --print-log
    Permitted Values | Type | boolean
     | Default | FALSE

    Cause ndb_restore to output its log to stdout.

    • --print_meta
    Command-Line Format | --print-meta
    Permitted Values | Type | boolean
     | Default | FALSE

    Print all metadata to stdout.

    • print-sql-log
    Introduced | 5.7.16-ndb-7.5.4
    Command-Line Format | print-sql-log
    Permitted Values | Type | boolean
     | Default | FALSE

    Log SQL statements to stdout. Use the option to enable; normally this behavior is disabled. The option checks before attempting to log whether all the tables being restored have explicitly defined primary keys; queries on a table having only the hidden primary key implemented by NDB cannot be converted to valid SQL.

    The --print-sql-log option was added in NDB 7.5.4. (Bug #13511949)

    • --progress-frequency=N
    Command-Line Format | --progress-frequency=#
    Permitted Values | Type | numeric
     | Default | 0
     | Min Value | 0
     | Max Value | 65535

    Print a status report each N seconds while the backup is in progress. 0 (the default) causes no status reports to be printed. The maximum is 65535.

    • --promote-attributes, -A
    Command-Line Format | --promote-attributes

    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 16.4.1.10.2, “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:

        1. Prepare the table to which the backup is to be restored. ndb_restore cannot be used to re-create the table with a different definition from the original; this means that you must either create the table manually, or alter the columns which you wish to promote using ALTER TABLE after restoring the table metadata but before restoring the data.

        2. Invoke ndb_restore with the --promote-attributes option (short form -A) when restoring the table data. Attribute promotion does not occur if this option is not used; instead, the restore operation fails with an error.

    When converting between character data types and TEXT or BLOB, only conversions between character types (CHAR and VARCHAR) and binary types (BINARY and VARBINARY) can be performed at the same time. For example, you cannot promote an INT column to BIGINT while promoting a VARCHAR column to TEXT in the same invocation of ndb_restore.

    Converting between TEXT columns using different character sets is not supported, and is expressly disallowed.

    When performing conversions of character or binary types to TEXT or BLOB with ndb_restore, you may notice that it creates and uses one or more staging tables named table_name$STnode_id. These tables are not needed afterwards, and are normally deleted by ndb_restore following a successful restoration.

    • --rebuild-indexes
    Command-Line Format | --rebuild-indexes

    Enable multi-threaded rebuilding of the ordered indexes while restoring a native NDB backup. The number of threads used for building ordered indexes by ndb_restore with this option is controlled by the BuildIndexThreads data node configuration parameter and the number of LDMs. It is necessary to use this option only for the first run of ndb_restore; this causes all ordered indexes to be rebuilt without using --rebuild-indexes again when restoring subsequent nodes. You should use this option prior to inserting new rows into the database; otherwise, it is possible for a row to be inserted that later causes a unique constraint violation when trying to rebuild the indexes.

    Building of ordered indices is parallelized with the number of LDMs by default. Offline index builds performed during node and system restarts can be made faster using the BuildIndexThreads data node configuration parameter; this parameter has no effect on dropping and rebuilding of indexes by ndb_restore, which is performed online.

    Rebuilding of unique indexes uses disk write bandwidth for redo logging and local checkpointing. An insufficient amount of this bandwith can lead to redo buffer overload or log overload errors. In such cases you can run ndb_restore --rebuild-indexes again; the process resumes at the point where the error occurred. You can also do this when you have encountered temporary errors. You can repeat execution of ndb_restore --rebuild-indexes indefinitely; you may be able to stop such errors by reducing the value of --parallelism. If the problem is insufficient space, you can increase the size of the redo log (FragmentLogFileSize node configuration parameter), or you can increase the speed at which LCPs are performed (MaxDiskWriteSpeed and related parameters), in order to free space more quickly.

    • --restore_data, -r
    Command-Line Format | --restore-data
    Permitted Values | Type | boolean
     | Default | FALSE

    Output NDB table data and logs.

    • --restore_epoch, -e
    Command-Line Format | --restore-epoch

    Add (or restore) epoch information to the cluster replication status table. This is useful for starting replication on an NDB 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 21.6.9, “NDB Cluster Backups With NDB Cluster Replication”.)

    • --restore_meta, -m
    Command-Line Format | --restore-meta
    Permitted Values | Type | boolean
     | Default | FALSE

    This option causes ndb_restore to print NDB table metadata.

    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 --restore_meta (-m) option. Restoring the metadata need be done only on a single data node; this is sufficient to restore it to the entire cluster.

    In older versions of NDB Cluster, tables whose schemas were restored using this option used the same number of partitions as they did on the original cluster, even if it had a differing number of data nodes from the new cluster. In NDB 7.5.2 and later, when restoring metadata, this is no longer an issue; ndb_restore now uses the default number of partitions for the target cluster, unless the number of local data manager threads is also changed from what it was for data nodes in the original cluster.

        Note
        The cluster should have an empty database when starting to restore a backup. (In other words, you should start the data nodes with --initial prior to performing the restore.)

    • --restore-privilege-tables
    Command-Line Format | --restore-privilege-tables
    Permitted Values | Type | boolean
     | Default | FALSE

    ndb_restore does not by default restore distributed MySQL privilege tables. This option causes ndb_restore to restore the privilege tables.

    This works only if the privilege tables were converted to NDB before the backup was taken. For more information, see Section 21.5.15, “Distributed MySQL Privileges for NDB Cluster”.

    • --rewrite-database=olddb,newdb
    Command-Line Format | --rewrite-database=olddb,newdb
    Permitted Values | Type | string
     | Default | none

    This option makes it possible to restore to a database having a different name from that used in the backup. For example, if a backup is made of a database named products, you can restore the data it contains to a database named inventory, use this option as shown here (omitting any other options that might be required):

        shell> ndb_restore --rewrite-database=product,inventory

    The option can be employed multiple times in a single invocation of ndb_restore. Thus it is possible to restore simultaneously from a database named db1 to a database named db2 and from a database named db3 to one named db4 using --rewrite-database=db1,db2 --rewrite-database=db3,db4. Other ndb_restore options may be used between multiple occurrences of --rewrite-database.

    In the event of conflicts between multiple --rewrite-database options, the last --rewrite-database option used, reading from left to right, is the one that takes effect. For example, if --rewrite-database=db1,db2 --rewrite-database=db1,db3 is used, only --rewrite-database=db1,db3 is honored, and --rewrite-database=db1,db2 is ignored. It is also possible to restore from multiple databases to a single database, so that --rewrite-database=db1,db3 --rewrite-database=db2,db3 restores all tables and data from databases db1 and db2 into database db3.

        Important
        When restoring from multiple backup databases into a single target database using --rewrite-database, no check is made for collisions between table or other object names, and the order in which rows are restored is not guaranteed. This means that it is possible in such cases for rows to be overwritten and updates to be lost.

    • --skip-broken-objects
    Command-Line Format | --skip-broken-objects

    This option causes ndb_restore to ignore corrupt tables while reading a native NDB backup, and to continue restoring any remaining tables (that are not also corrupted). Currently, the --skip-broken-objects option works only in the case of missing blob parts tables.

    • --skip-table-check, -s
    Command-Line Format | --skip-table-check

    It is possible to restore data without restoring table metadata. By default when doing this, ndb_restore fails with an error if a mismatch is found between the table data and the table schema; this option overrides that behavior.

    Some of the restrictions on mismatches in column definitions when restoring data using ndb_restore are relaxed; when one of these types of mismatches is encountered, ndb_restore does not stop with an error as it did previously, but rather accepts the data and inserts it into the target table while issuing a warning to the user that this is being done. This behavior occurs whether or not either of the options --skip-table-check or --promote-attributes is in use. These differences in column definitions are of the following types:

        • Different COLUMN_FORMAT settings (FIXED, DYNAMIC, DEFAULT)

        • Different STORAGE settings (MEMORY, DISK)

        • Different default values

        • Different distribution key settings

    • --skip-unknown-objects
    Command-Line Format | --skip-unknown-objects

    This option causes ndb_restore to ignore any schema objects it does not recognize while reading a native NDB backup. This can be used for restoring a backup made from a cluster running (for example) NDB 7.6 to a cluster running NDB Cluster 7.5.

    • --tab=dir_name, -T dir_name
    Command-Line Format | --tab=dir_name
    Permitted Values | Type | directory name

    Causes --print_data to create dump files, one per table, each named tbl_name.txt. It requires as its argument the path to the directory where the files should be saved; use . for the current directory.

    • --verbose=#
    Command-Line Format | --verbose=#
    Permitted Values | Type | numeric
     | Default | 1
     | Min Value | 0
     | Max Value | 255

    Sets the level for the verbosity of the output. The minimum is 0; the maximum is 255. The default value is 1.

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

    Important

    After using ndb_restore to initialize an NDB Cluster for use in circular replication, binary logs on the SQL node acting as the replication slave are not automatically created, and you must cause them to be created manually. To cause the binary logs to be created, issue a SHOW TABLES statement on that SQL node before running START SLAVE. This is a known issue in NDB Cluster.

  Restoring to a different number of data nodes

It is possible to restore from an NDB backup to a cluster having a different number of data nodes than the original from which the backup was taken. The following two sections discuss, respectively, the cases where the target cluster has a lesser or greater number of data nodes than the source of the backup.

Restoring to Fewer Nodes Than the Original

    You can restore to a cluster having fewer data nodes than the original provided that the larger number of nodes is an even multiple of the smaller number. In the following example, we use a backup taken on a cluster having four data nodes to a cluster having two data nodes.

        1. The management server for the original cluster is on host host10. The original cluster has four data nodes, with the node IDs and host names shown in the following extract from the management server's config.ini file:

            [ndbd]
            NodeId=2
            HostName=host2
            [ndbd]
            NodeId=4
            HostName=host4
            [ndbd]
            NodeId=6
            HostName=host6
            [ndbd]
            NodeId=8
            HostName=host8

        We assume that each data node was originally started with ndbmtd --ndb-connectstring=host10 or the equivalent.

        2. Perform a backup in the normal manner. See Section 21.5.3.2, “Using The NDB Cluster Management Client to Create a Backup”, for information about how to do this.

        3. The files created by the backup on each data node are listed here, where N is the node ID and B is the backup ID.

            • BACKUP-B-0.N.Data

            • BACKUP-B.N.ctl

            • BACKUP-B.N.log

        These files are found under BackupDataDir/BACKUP/BACKUP-B, on each data node. For the rest of this example, we assume that the backup ID is 1.

        Have all of these files available for later copying to the new data nodes (where they can be accessed on the data node's local file system by ndb_restore). It is simplest to copy them all to a single location; we assume that this is what you have done.

        4. The management server for the target cluster is on host host20, and the target has two data nodes, with the node IDs and host names shown, from the management server config.ini file on host20:

            [ndbd]
            NodeId=3
            hostname=host3
            [ndbd]
            NodeId=5
            hostname=host5

        Each of the data node processes on host3 and host5 should be started with ndbmtd -c host20 --initial or the equivalent, so that the new (target) cluster starts with clean data node file systems.

        5. Copy two different sets of two backup files to each of the target data nodes. For this example, copy the backup files from nodes 2 and 6 from the original cluster to node 3 in the target cluster. These files are listed here:

            • BACKUP-1-0.2.Data

            • BACKUP-1.2.ctl

            • BACKUP-1.2.log

            • BACKUP-1-0.6.Data

            • BACKUP-1.6.ctl

            • BACKUP-1.6.log

        Then copy the backup files from nodes 4 and 8 to node 5; these files are shown in the following list:

            • BACKUP-1-0.4.Data

            • BACKUP-1.4.ctl

            • BACKUP-1.4.log

            • BACKUP-1-0.8.Data

            • BACKUP-1.8.ctl

            • BACKUP-1.8.log

        For the remainder of this example, we assume that the respective backup files have been saved to the directory /BACKUP-1 on each of nodes 3 and 5.

        6. On each of the two target data nodes, you must restore from both sets of backups. First, restore the backups from nodes 2 and 6 to node 3 by invoking ndb_restore on host3 as shown here:

            shell> ndb_restore -c host20 --nodeid=2 --backupid=1 --restore_data --backup_path=/BACKUP-1
            shell> ndb_restore -c host20 --nodeid=4 --backupid=1 --restore_data --backup_path=/BACKUP-1

        Then restore the backups from nodes 4 and 8 to node 5 by invoking ndb_restore on host5, like this:

            shell> ndb_restore -c host20 --nodeid=6 --backupid=1 --restore_data --backup_path=/BACKUP-1
            shell> ndb_restore -c host20 --nodeid=8 --backupid=1 --restore_data --backup_path=/BACKUP-1

Restoring to More Nodes Than the Original

    The node ID specified for a given ndb_restore command is that of the node in the original backup and not that of the data node to restore it to. When performing a backup using the method described in this section, ndb_restore connects to the management server and obtains a list of data nodes in the cluster the backup is being restored to. The restored data is distributed accordingly, so that the number of nodes in the target cluster does not need to be to be known or calculated when performing the backup.

        Note

        When changing the total number of LCP threads or LQH threads per node group, you should recreate the schema from backup created using mysqldump.

        1. Create the backup of the data. You can do this by invoking the ndb_mgm client START BACKUP command from the system shell, like this:

            shell> ndb_mgm -e "START BACKUP 1"

        This assumes that the desired backup ID is 1.

        2. Create a backup of the schema. In NDB 7.5.2 and later, this step is necessary only if the total number of LCP threads or LQH threads per node group is changed.

            shell> mysqldump --no-data --routines --events --triggers --databases > myschema.sql

            Important
            Once you have created the NDB native backup using ndb_mgm, you must not make any schema changes before creating the backup of the schema, if you do so.

        3. Copy the backup directory to the new cluster. For example if the backup you want to restore has ID 1 and BackupDataDir = /backups/node_nodeid, then the path to the backup on this node is /backups/node_1/BACKUP/BACKUP-1. Inside this directory there are three files, listed here:

            • BACKUP-1-0.1.Data

            • BACKUP-1.1.ctl

            • BACKUP-1.1.log

        You should copy the entire directory to the new node.

        If you needed to create a schema file, copy this to a location on an SQL node where it can be read by mysqld.

    There is no requirement for the backup to be restored from a specific node or nodes.

    To restore from the backup just created, perform the following steps:

        1. Restore the schema.

            • If you created a separate schema backup file using mysqldump, import this file using the mysql client, similar to what is shown here:

                shell> mysql < myschema.sql

            When importing the schema file, you may need to specify the --user and --password options (and possibly others) in addition to what is shown, in order for the mysql client to be able to connect to the MySQL server.

            • If you did not need to create a schema file, you can re-create the schema using ndb_restore --restore_meta (short form -m), similar to what is shown here:

                shell> ndb_restore --nodeid=1 --backupid=1 --restore_meta --backup-path=/backups/node_1/BACKUP/BACKUP-1

            ndb_restore must be able to contact the management server; add the --ndb-connectstring option if and as needed to make this possible.

        2. Restore the data. This needs to be done once for each data node in the original cluster, each time using that data node's node ID. Assuming that there were 4 data nodes originally, the set of commands required would look something like this:

            ndb_restore --nodeid=1 --backupid=1 --restore_data --backup_path=/backups/node_1/BACKUP/BACKUP-1 --disable-indexes
            ndb_restore --nodeid=2 --backupid=1 --restore_data --backup_path=/backups/node_2/BACKUP/BACKUP-1 --disable-indexes
            ndb_restore --nodeid=3 --backupid=1 --restore_data --backup_path=/backups/node_3/BACKUP/BACKUP-1 --disable-indexes
            ndb_restore --nodeid=4 --backupid=1 --restore_data --backup_path=/backups/node_4/BACKUP/BACKUP-1 --disable-indexes

        These can be run in parallel.

        Be sure to add the --ndb-connectstring option as needed.

        3. Rebuild the indexes. These were disabled by the --disable-indexes option used in the commands just shown. Recreating the indexes avoids errors due to the restore not being consistent at all points. Rebuilding the indexes can also improve performance in some cases. To rebuild the indexes, execute the following command once, on a single node:

            shell> ndb_restore --nodeid=1 --backupid=1 --backup_path=/backups/node_1/BACKUP/BACKUP-1 --rebuild-indexes

        As mentioned previously, you may need to add the --ndb-connectstring option, so that ndb_restore can contact the management server.

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SEE ALSO
For more information, please refer to the MySQL Reference Manual, which may already be installed locally and which is also available online at http://dev.mysql.com/doc/.

AUTHOR
Oracle Corporation (http://dev.mysql.com/).