The optimizer considers star join optimization when appropriate and decides on star join plan based on cost considerations in order to come up with best execution plan for a star join query.

为了实现星型连接查询的最佳执行计划，优化器在适当的时候会考虑星型连接优化，并根据成本因素来决定星型连接计划。

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There are two methods of database query optimization: cost-based and response time-based query optimization, all of which can improve the efficiency of complex query.

数据库查询优化包括两方面，基于代价的查询优化和基于响应时光的查询优化，可以有效地提高庞杂查询的效力。

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