Optimizing Database Communication Parameters

By default, nodes in a database cluster communicate using the TCP proxy communication library.

comm_quota_size controls the size of data transmitted every time in each flow channel. Its default value is 1M. In a high concurrency scenario, you can increase its value to improve communication performance, but doing so consumes more memory. Optimize this parameter as needed. If you query the pg_total_memory_detail view of a DN and find that the memory used by the communication layer has reached the threshold of comm_usable_memory, set comm_quota_size to a small value, such as 512K.

comm_usable_memory controls the memory on a DN that can be used for database communication. The value of this parameter is only used for memory flow control. The default flow control value is 1 MB. If the memory usage exceeds half of the parameter value, the flow control value will be automatically changed to 0.5 MB. If only 20% of the memory specified by the parameter is available, the flow control value will be changed to the allowed minimum, 8 KB.