Specifying a Shard Using a Hint When You Execute a SQL Statement
DDM allows you to customize a hint to specify whether SQL statements are executed on one shard or multiple shards.
The following hint formats are supported:
- SQL statement executed on one shard: /*+db=<physical_db_name>*/ <your query>;
- SQL statement executed on multiple shards: /*+db={<physical_db_name1>, <physical_db_name2>,<physical_db_name3>......}*/ <your query>;
Example:
- SQL statement executed on one shard: /*+db=test_0000*/ select * from t1;
- SQL statement executed on multiple shards: /*+db={test_0001, test_0002, test_0003}*/ select * from t2;
Constraints:
- If the SQL statement is executed on multiple shards, the value of physical_db_name must be unique.
- The hint is valid only for SELECT, DML, and TRUNCATE statements.
- The hint works only under the text protocol, rather than the Prepare protocol.
Parent topic: Supported SQL Statements