NDB Cluster Configuration Files Restart Type N (NDB 8.0.13) This parameter is used to control the number of parallel scans that can be performed in the cluster. Each transaction coordinator can handle the number of parallel scans defined for this parameter. Each scan query is performed by scanning all partitions in parallel. Each partition scan uses a scan record in the node where the partition is located, the number of records being the value of this parameter times the number of nodes. The cluster should be able to sustain  MaxNoOfConcurrentScans  scans concurrently from all nodes in the cluster. Scans are actually performed in two cases. The first of these cases occurs when no hash or ordered indexes exists to handle the query, in which case the query is executed by performing a full table scan. The second case is encountered when there is no hash index to support the query but there is an ordered index. Using the ordered index means executing a parallel range scan. The order is kept on the local partitions only, so it is necessary to perform the index scan on all partitions. The default value of  MaxNoOfConcurrentScans  is 256. The maximum value is 500. Specifies the number of local scan records if many scans are not fully parallelized. When the number of local scan records is not provided, it is calculated as shown here: 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. This parameter sets the parallelization used in the copy phase of a node restart or system restart, when a node that is currently just starting is synchronised with a node that already has current data by copying over any changed records from the node that is up to date. Because full parallelism in such cases can lead to overload situations,  MaxParallelCopyInstances  provides a means to decrease it. This parameter’s default value 0. This value means that the effective parallelism is equal to the number of LDM instances in the node just starting as well as the node updating it. 4087 4 * MaxNoOfConcurrentScans * [# data nodes] + 2 • MaxNoOfLocalScans • MaxParallelCopyInstances Version (or later) NDB 8.0.13 Type or units integer Default 4 * MaxNoOfConcurrentScans * [# of data nodes] + 2 Range 32 - 4294967039 (0xFFFFFEFF) Deprecated NDB 8.0.19 Restart Type N (NDB 8.0.13) Version (or later) NDB 8.0.13 Type or units integer Default 0 Range 0 - 64 Restart Type N (NDB 8.0.13)