Although canonical examples use the vector representation as a key and value, there's no restriction on how you can define the value (such as an aggregate of a number of values).
虽然规范的示例使用矢量表达作为键和值，但是并没有限制您如何来定义值(例如一些值的汇总)。
This is a key that combines a number of columns to uniquely define the rows of a database table.
这个键组合了多列，唯一地定义一个数据库表的行。
This is a key that combines a number of columns to uniquely define the rows of a database table.
这个键组合了多列，唯一地定义一个数据库表的行。
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