While the semantics of the input arguments remain the same as in the Data Distribution Policy, the return value now contains an array of slice identifiers instead of a single one.
虽然输入参数的语义与数据分布策略内的相同，返回值现在包含一个片标识的数组，而非单一一个片标识。
2
Just as before, there are three ways to generate a database partition map: uniform, weighted through a distributionarray (using distfile), and user specified (using targetmap).