The counters table provides running totals of events such as reads and writes for specific kernel blocks and data nodes. Counts are kept from the most recent node start or restart; a node start or restart resets all counters on that node. Not all kernel blocks have all types of counters.

The following table provides information about the columns in the counters table. For each column, the table shows the name, data type, and a brief description. Additional information can be found in the notes following the table.

Each counter is associated with a particular NDB kernel block. Prior to MySQL Cluster NDB 7.2.0, this was limited to either the DBLQH kernel block or the DBTC kernel block.

The OPERATIONS counter is associated with the DBLQH (local query handler) kernel block (see The DBLQH Block).

The ATTRINFO, TRANSACTIONS, COMMITS, READS, SIMPLE_READS, WRITES, ABORTS, TABLE_SCANS, and RANGE_SCANS counters are associated with the DBTC (transaction co-ordinator) kernel block (see The DBTC Block).

MySQL Cluster NDB 7.2.0, as part of its implementation of distributed pushed-down joins, adds the LOCAL_TABLE_SCANS_SENT, READS_RECEIVED, PRUNED_RANGE_SCANS_RECEIVED, RANGE_SCANS_RECEIVED, LOCAL_READS_SENT, CONST_PRUNED_RANGE_SCANS_RECEIVED, LOCAL_RANGE_SCANS_SENT, REMOTE_READS_SENT, REMOTE_RANGE_SCANS_SENT, READS_NOT_FOUND, SCAN_BATCHES_RETURNED, TABLE_SCANS_RECEIVED, and SCAN_ROWS_RETURNED counters. These counters are associated with the DBSPJ (select push-down join) kernel block (see The DBSPJ Block).