# Modifying TiDB System Variables

+ Modify variable at global scope:
  + **`SET @@global.tidb_distsql_scan_concurrency = 10;`**
  + **`SET  GLOBAL tidb_distsql_scan_concurrency = 10;`**

+ Modify variable at session scope:
  + **`SET tidb_distsql_scan_concurrency = 10;`**
  + **`SET SESSION tidb_distsql_scan_concurrency = 10;`**

-------------------------------------------------------------
Equivalent statements to change a variable at `global` scope:
```
SET @@GLOBAL.tidb_distsql_scan_concurrency = 10;
SET GLOBAL TIDB_distsql_scan_concurrency = 10;
```

Equivalent statements to change a variable at `session` scope:
```
SET tidb_distsql_scan_concurrency = 10;
SET SESSION tidb_distsql_scan_concurrency = 10;
```

Please refer to `https://docs.pingcap.com/tidb/stable/system-variables` for detail.