great many updates, it may be necessary for the ratio of TC threads to LDM threads to approach 1 (for example, 3 TC threads to 4 LDM threads). 

Setting tc  to 0 causes TC handling to be done by the main thread. In most cases, this is effectively the same as setting it to 1. 

Range: 0-64 ( NDB 8.0.22 and earlier : 0 - 32) 

• main : Data dictionary and transaction coordinator ( DBDIH  and DBTC  kernel blocks), providing schema management. Prior to NDB 8.0.23, this was always handled by a single dedicated thread, beginning ith NDB 8.0.23, it is also possible to specify zero or two main threads. 

Range: 

• NDB 8.0.22 and earlier : 1 only. 

NDB 8.0.23 and later : 0-2. 

Setting main  to 0 and rep  to 1 causes the main  blocks to be placed into the rep  thread; the combined thread is shown in the ndbinfo.threads  table as main_rep . This is effectively the same as setting rep  equal to 1 and main  equal to 0. 

It is also possible to set both main  and rep  to 0, in which case both threads are placed in the first recv  thread; the resulting combined thread is named main_rep_recv  in the threads  table. 

• recv : Receive thread ( CMVMI  kernel block). Each receive thread handles one or more sockets for communicating with other nodes in an NDB Cluster, with one socket per node. NDB Cluster supports multiple receive threads; the maximum is 16 such threads. 

Range: 

• NDB 8.0.22 and earlier : 1 - 16 

• NDB 8.0.23 and later : 1 - 64 

• send : Send thread ( CMVMI  kernel block). To increase throughput, it is possible to perform sends from one or more separate, dedicated threads (maximum 8). 

In NDB 8.0.20 and later, due to changes in the multithreading implementation, using many send threads can have an adverse effect on scalability. 

Previously, all threads handled their own sending directly; this can still be made to happen by setting the number of send threads to 0 (this also happens when MaxNoOfExecutionThreads  is set less than 10). While doing so can have an adeverse impact on throughput, it can also in some cases provide decreased latency. 

Range: 

• NDB 8.0.22 and earlier : 0 - 16 

• NDB 8.0.23 and later : 0 - 64 

