Specifies the shard key for this class.
Usage
Until sharded classes are fully implemented, InterSystems recommends creating sharded tables from SQL, not from the object side. However, if you look at a class generated by creating a sharded table, you may see code such as the following:
/// ShardKey index for Sharded table, auto-generated by DDL CREATE TABLE statement
Index ShardKey On DeptNum [ Abstract, CoshardWith = User.Department, ShardKey, SqlName = %ShardKey ];
In this example, the DeptNum property is the shard key of the current class.
