From the performance perspective, this is considered a very efficient join operation, because the cost for scanning the inner table is optimal via unique access through a unique index.
从性能的角度来看，这被认为是一个非常有效的联接操作，因为通过贯穿唯一索引的唯一访问扫描内部表的成本是最优的。
These results show that the minimum cost and optimal value of the diet is $0.90.
这些结果说明日常饮食最低成本（优化值）是 0.90 美元。
The optimizer relies on statistics to properly cost alternative query execution plans (QEPs) and choose the most optimal plan.
优化器是依靠统计信息来计算可选查询执行计划（QEP）的开销，同时选择出最优的计划。
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