MySQL Cluster Manager 8.4.3 User Manual
It is possible using MySQL Cluster Manager to perform a partial restore of a
MySQL NDB Cluster—that is, to restore from a backup in which
backup images from one or more data nodes are not available.
This is required if we wish to restore
mycluster to backup number 6, since an
image for this backup is available only for node 1, as can be
seen in the output of list
backups in the mcm client
:
mcm> list backups mycluster; +----------+--------+---------+---------------------+--------+---------+ | BackupId | NodeId | Host | Timestamp | Parts | Comment | +----------+--------+---------+---------------------+--------+---------+ | 1 | 1 | tonfisk | 2020-12-04 12:03:52 | 1 | | | 1 | 2 | tonfisk | 2020-12-04 12:03:52 | 1 | | | 2 | 1 | tonfisk | 2020-12-04 12:04:15 | 1 | | | 2 | 2 | tonfisk | 2020-12-04 12:04:15 | 1 | | | 3 | 1 | tonfisk | 2020-12-04 12:17:41 | 1 | | | 3 | 2 | tonfisk | 2020-12-04 12:17:41 | 1 | | | 4 | 1 | tonfisk | 2020-12-12 14:24:35 | 1 | | | 4 | 2 | tonfisk | 2020-12-12 14:24:35 | 1 | | | 5 | 1 | tonfisk | 2020-12-12 14:31:31 | 1 | | | 5 | 2 | tonfisk | 2020-12-12 14:31:31 | 1 | | | 6 | 1 | tonfisk | 2020-12-12 14:32:09 | 1 | | +----------+--------+---------+---------------------+--------+---------+ 11 rows in set (0.08 sec)
To perform a restore of only those nodes for which we have
images (in this case, node 1 only), we can use the
--skip-nodeid
option when executing a restore
cluster command. This option causes one or more
nodes to be skipped when performing the restore. Assuming that
mycluster has been cleared of data (as
described earlier in this section), we can perform a restore
that skips node 2 as shown here:
mcm> restore cluster --backupid=6 --skip-nodeid=2 mycluster;
+--------------------------------+
| Command result |
+--------------------------------+
| Restore completed successfully |
+--------------------------------+
1 row in set (17.06 sec)
Because we excluded node 2 from the restore process, no data
has been distributed to it. To cause MySQL NDB Cluster data to be
distributed to any such excluded or skipped nodes following a
partial restore, it is necessary to redistribute the data
manually by executing an
ALTER
ONLINE TABLE ... REORGANIZE PARTITION statement in
the mysql client for each
NDB table in the cluster. To
obtain a list of NDB tables from the
mysql client, you can use multiple
SHOW TABLES statements or a
query such as this one:
SELECT CONCAT('' TABLE_SCHEMA, '.', TABLE_NAME)
FROM INFORMATION_SCHEMA.TABLES
WHERE ENGINE='ndbcluster';
You can generate the necessary SQL statements using a more elaborate version of the query just shown, such the one employed here:
mysql>SELECT->CONCAT('ALTER ONLINE TABLE `', TABLE_SCHEMA,->'`.`', TABLE_NAME, '` REORGANIZE PARTITION;')->AS Statement->FROM INFORMATION_SCHEMA.TABLES->WHERE ENGINE='ndbcluster';+--------------------------------------------------------------------------+ | Statement | +--------------------------------------------------------------------------+ | ALTER ONLINE TABLE `mysql`.`ndb_apply_status` REORGANIZE PARTITION; | | ALTER ONLINE TABLE `mysql`.`ndb_index_stat_head` REORGANIZE PARTITION; | | ALTER ONLINE TABLE `mysql`.`ndb_index_stat_sample` REORGANIZE PARTITION; | | ALTER ONLINE TABLE `db1`.`n1` REORGANIZE PARTITION; | | ALTER ONLINE TABLE `db1`.`n2` REORGANIZE PARTITION; | | ALTER ONLINE TABLE `db1`.`n3` REORGANIZE PARTITION; | | ALTER ONLINE TABLE `test`.`n1` REORGANIZE PARTITION; | | ALTER ONLINE TABLE `test`.`n2` REORGANIZE PARTITION; | | ALTER ONLINE TABLE `test`.`n3` REORGANIZE PARTITION; | | ALTER ONLINE TABLE `test`.`n4` REORGANIZE PARTITION; | +--------------------------------------------------------------------------+ 10 rows in set (0.09 sec)