Join plan directives that force optimizer to use the designated join method to join tables in the query, either nested loop join, sort merge join, or dynamic hash join.

连接计划指示，强制优化器使用指定的连接方法来连接查询中的表，要么是嵌套循环连接、分类合并连接，要么是动态哈希连接。

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If the query includes a join, the optimizer must determine the join plan (hash, sort merge, or nested loop), and the order in which tables are evaluated or joined.

如果该查询包含了连接，那么优化器就必须确定连接计划(hash、sort merge或nested loop)，以及评估或连接表的次序。

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