# Using Tiflash

+ Add a TiFlash replica of a table
  + `ALTER TABLE T1 SET TIFLASH REPLICA 2;` 
+ The execution plan shows the cop [tiflash] instruction that the query is completed on TiFlash
  + `└─TableFullScan_16 | 1.00 | 1 | cop[tiflash] | table:t ` 
+ Delete TiFlash replica
  + `ALTER TABLE T1 SET TIFLASH REPLICA 0;` 
+ Manually select to execute SQL statements on TiFlash
  + `SELECT /*+ read_from_storage(tiflash[T1]) */ ... FROM T1;` 
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First, confirm that the current TiDB version supports TiFlash. Otherwise, you need to upgrade the TiDB cluster to v5.0 later version.
Execute the tiup <cluster-version>ctl:pd -u http<pd_ip>://<pd_port>:config set enable-placement-rules true command to enable the placement rules feature of the PD. Or execute the corresponding command via pd-ctl.