NDB Cluster Configuration Files For queries using a unique hash index, another temporary set of operation records is used during a query’s execution phase. This parameter sets the size of that pool of records. Thus, this record is allocated only while executing a part of a query. As soon as this part has been executed, the record is released. The state needed to handle aborts and commits is handled by the normal operation records, where the pool size is set by the parameter  MaxNoOfConcurrentOperations . The default value of this parameter is 8192. Only in rare cases of extremely high parallelism using unique hash indexes should it be necessary to increase this value. Using a smaller value is possible and can save memory if the DBA is certain that a high degree of parallelism is not required for the cluster. This parameter is deprecated as of NDB 8.0.19, and is subject to removal in a future NDB Cluster release. In addition, this parameter is incompatible with the  TransactionMemory  parameter; if you try to set values for both parameters in the cluster configuration file ( config.ini ), the management server refuses to start. The default value of  MaxNoOfFiredTriggers  is 4000, which is sufficient for most situations. In some cases it can even be decreased if the DBA feels certain the need for parallelism in the cluster is not high. A record is created when an operation is performed that affects a unique hash index. Inserting or deleting a record in a table with unique hash indexes or updating a column that is part of a unique hash index fires an insert or a delete in the index table. The resulting record is used to represent this index table operation while waiting for the original operation that fired it to complete. This operation is short- lived but can still require a large number of records in its pool for situations with many parallel write operations on a base table containing a set of unique hash indexes. This parameter is deprecated as of NDB 8.0.19, and is subject to removal in a future NDB Cluster release. In addition, this parameter is incompatible with the  TransactionMemory  parameter; if you try to set values for both parameters in the cluster configuration file ( config.ini ), the management server refuses to start. • TransactionBufferMemory • MaxNoOfFiredTriggers Version (or later) NDB 8.0.13 Type or units integer Default 4000 Range 0 - 4294967039 (0xFFFFFEFF) Deprecated NDB 8.0.19 Restart Type N (NDB 8.0.13) Version (or later) NDB 8.0.13 Type or units bytes Default 1M Range 1K - 4294967039 (0xFFFFFEFF) 4082