The count(1) statement counts the total number of rows in a table. Improving the degree of concurrency can significantly improve the speed. To modify the concurrency, refer to the tidb_distsql_scan_concurrency document. But it also depends on the CPU and I/O resources. TiDB accesses TiKV in every query. When the amount of data is small, all MySQL is in memory, and TiDB needs to conduct a network access.
Recommendations:
- Improve the hardware configuration. See Software and Hardware Requirements.
- Improve the concurrency. The default value is 10. You can improve it to 50 and have a try. But usually the improvement is 2-4 times of the default value.
- Test the
countin the case of large amount of data. - Optimize the TiKV configuration. See Tune TiKV Thread Performance and Tune TiKV Memory Performance.
- Enable the Coprocessor Cache.