Type or units integer Default 32K Range 32 - 4294967039 (0xFFFFFEFF) Restart Type N (NDB 8.0.13) It is a good idea to adjust the value of this parameter according to the size and number of transactions. When performing transactions which involve only a few operations and records, the default value for this parameter is usually sufficient. Performing large transactions involving many records usually requires that you increase its value. Records are kept for each transaction updating cluster data, both in the transaction coordinator and in the nodes where the actual updates are performed. These records contain state information needed to find UNDO records for rollback, lock queues, and other purposes. This parameter should be set at a minimum to the number of records to be updated simultaneously in transactions, divided by the number of cluster data nodes. For example, in a cluster which has four data nodes and which is expected to handle one million concurrent updates using transactions, you should set this value to 1000000 / 4 = 250000. To help provide resiliency against failures, it is suggested that you set this parameter to a value that is high enough to permit an individual data node to handle the load for its node group. In other words, you should set the value equal to  total number of concurrent operations / number of node groups . (In the case where there is a single node group, this is the same as the total number of concurrent operations for the entire cluster.) Because each transaction always involves at least one operation, the value of MaxNoOfConcurrentOperations  should always be greater than or equal to the value of MaxNoOfConcurrentTransactions . Read queries which set locks also cause operation records to be created. Some extra space is allocated within individual nodes to accommodate cases where the distribution is not perfect over the nodes. When queries make use of the unique hash index, there are actually two operation records used per record in the transaction. The first record represents the read in the index table and the second handles the operation on the base table. The default value is 32768. This parameter actually handles two values that can be configured separately. The first of these specifies how many operation records are to be placed with the transaction coordinator. The second part specifies how many operation records are to be local to the database. A very large transaction performed on an eight-node cluster requires as many operation records in the transaction coordinator as there are reads, updates, and deletes involved in the transaction. However, the operation records of the are spread over all eight nodes. Thus, if it is necessary to configure the system for one very large transaction, it is a good idea to configure the two parts separately. MaxNoOfConcurrentOperations  is always used to calculate the number of operation records in the transaction coordinator portion of the node. It is also important to have an idea of the memory requirements for operation records. These consume about 1KB per record. • MaxNoOfLocalOperations Version (or later) NDB 8.0.13 4080 NDB Cluster Configuration Files