This document introduces how to tune the performance of TiFlash, including planning machine resources and tuning TiDB parameters.
If you want to save machine resources and have no requirement on isolation, you can use the method that combines the deployment of both TiKV and TiFlash. It is recommended that you save enough resources for TiKV and TiFlash respectively, and do not share disks.
For the TiDB node dedicated to OLAP/TiFlash, it is recommended that you increase the value of the
tidb_distsql_scan_concurrencyconfiguration item for this node to
80:set @@tidb_distsql_scan_concurrency = 80;
Enable the optimization for TiDB Operator such as the aggregate pushdown of
UNION:set @@tidb_opt_agg_push_down = 1;