ndbinfo is a database storing containing information specific to MySQL Cluster, available beginning with MySQL Cluster NDB 7.1.1.

This database contains a number of tables, each providing a different sort of data about MySQL Cluster node status, resource usage, and operations. You can find more detailed information about each of these tables in the next several sections.

ndbinfo is included with MySQL Cluster support in the MySQL Server; no special compilation or configuration steps are required; the tables are created by the MySQL Server when it connects to the cluster. You can verify that ndbinfo support is active in a given MySQL Server instance using SHOW PLUGINS; if ndbinfo support is enabled, you should see a row containing ndbinfo in the Name column and ACTIVE in the Status column, as shown here (emphasized text):

mysql> SHOW PLUGINS;
+------------+----------+----------------+---------+---------+
| Name       | Status   | Type           | Library | License |
+------------+----------+----------------+---------+---------+
| binlog     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| partition  | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| ARCHIVE    | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| BLACKHOLE  | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| CSV        | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| FEDERATED  | DISABLED | STORAGE ENGINE | NULL    | GPL     |
| MEMORY     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| InnoDB     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| MyISAM     | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| MRG_MYISAM | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| ndbcluster | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
| ndbinfo    | ACTIVE   | STORAGE ENGINE | NULL    | GPL     |
+------------+----------+----------------+---------+---------+
12 rows in set (0.00 sec)

You can also do this by checking the output of SHOW ENGINES for a line including ndbinfo in the Engine column and YES in the Support column, as shown here (emphasized text):

mysql> SHOW ENGINES;
+------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine     | Support | Comment                                                        | Transactions | XA   | Savepoints |
+------------+---------+----------------------------------------------------------------+--------------+------+------------+
| ndbcluster | YES     | Clustered, fault-tolerant tables                               | YES          | NO   | NO         |
| MRG_MYISAM | YES     | Collection of identical MyISAM tables                          | NO           | NO   | NO         |
| ndbinfo    | YES     | MySQL Cluster system information storage engine                | NO           | NO   | NO         |
| CSV        | YES     | CSV storage engine                                             | NO           | NO   | NO         |
| MEMORY     | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         |
| FEDERATED  | NO      | Federated MySQL storage engine                                 | NULL         | NULL | NULL       |
| ARCHIVE    | YES     | Archive storage engine                                         | NO           | NO   | NO         |
| InnoDB     | YES     | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |
| MyISAM     | DEFAULT | Default engine as of MySQL 3.23 with great performance         | NO           | NO   | NO         |
| BLACKHOLE  | YES     | /dev/null storage engine (anything you write to it disappears) | NO           | NO   | NO         |
+------------+---------+----------------------------------------------------------------+--------------+------+------------+
10 rows in set (0.00 sec)

If ndbinfo support is enabled, then you can access ndbinfo via SQL statements in mysql or another MySQL client. For example, you can see ndbinfo listed in the output of SHOW DATABASES, as shown here:

mysql> SHOW DATABASES;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| ndbinfo            |
| test               |
+--------------------+
4 rows in set (0.00 sec)

If the mysqld process was not started with the --ndbcluster option, ndbinfo is not available and is not displayed by SHOW DATABASES. If mysqld was formerly connected to a MySQL Cluster but the cluster becomes unavailable (due to events such as cluster shutdown, loss of network connectivity, and so forth), ndbinfo and its tables remain visible, but an attempt to access any tables (other than blocks or config_params) fails with Got error 157 'Connection to NDB failed' from NDBINFO.

You can select the ndbinfo database with a USE statement, and then issue a SHOW TABLES statement to obtain a list of tables, just as for any other database, like this:

mysql> USE ndbinfo;
Database changed

mysql> SHOW TABLES;
+-------------------+
| Tables_in_ndbinfo |
+-------------------+
| blocks            |
| config_params     |
| counters          |
| logbuffers        |
| logspaces         |
| memoryusage       |
| nodes             |
| resources         |
| transporters      |
+-------------------+
9 rows in set (0.00 sec)

You can execute SELECT statements against these tables, just as you would normally expect:

mysql> SELECT * FROM memoryusage;
+---------+--------------+------+-------+
| node_id | DATA_MEMORY  | used | max   |
+---------+--------------+------+-------+
|       1 | DATA_MEMORY  | 3230 |  6408 |
|       2 | DATA_MEMORY  | 3230 |  6408 |
|       1 | INDEX_MEMORY |   16 | 12832 |
|       2 | INDEX_MEMORY |   16 | 12832 |
+---------+--------------+------+-------+
4 rows in set (0.37 sec)

More complex queries are possible, as shown here:

mysql> SELECT SUM(used) as 'Data Memory Used, All Nodes' 
     >     FROM memoryusage 
     >     WHERE DATA_MEMORY = 'DATA_MEMORY';
+-----------------------------+
| Data Memory Used, All Nodes |
+-----------------------------+
|                        6460 |
+-----------------------------+
1 row in set (0.37 sec)

mysql> SELECT SUM(max) as 'Total IndexMemory Available' 
     >     FROM memoryusage 
     >     WHERE DATA_MEMORY = 'INDEX_MEMORY';
+-----------------------------+
| Total IndexMemory Available |
+-----------------------------+
|                       25664 |
+-----------------------------+
1 row in set (0.33 sec)

ndbinfo table and column names are case sensitive (as is the name of the ndbinfo database itself). These identifiers are in lower case. Trying to use the wrong lettercase results in an error, as shown in this example:

mysql> SELECT * FROM nodes;
+---------+--------+---------+-------------+
| node_id | uptime | status  | start_phase |
+---------+--------+---------+-------------+
|       1 |  13602 | STARTED |           0 |
|       2 |     16 | STARTED |           0 |
+---------+--------+---------+-------------+
2 rows in set (0.04 sec)

mysql> SELECT * FROM Nodes;
ERROR 1146 (42S02): Table 'ndbinfo.Nodes' doesn't exist