SQL查询的优化利用了一些复杂的功能，例如：查询重写、多连接(join)方法、详细的统计、并行性等。
The optimization of SQL queries utilize sophisticated features, such as: query rewrite, multiple join methods, detailed statistics, parallelism etc.
您可以利用DB2 9.5 中的多列统计信息的扩展用途来为优化器提供更多的信息，从而使优化器更好地估计基数，选择最佳的查询访问计划。
You can leverage the extended use of multi-column statistics in DB2 9.5 to provide the optimizer more information to better estimate the cardinality in order to choose an optimal query access plan.
多连接查询优化是提高数据库性能的关键问题之一。
Query optimization for large join queries is one of the key factors to improving the performance of database systems.
多连接查询优化是并行数据库系统的核心问题。
The multi-join query optimization is the critical problem of parallel query optimization in parallel database system.
因此，如何能量高效地对无线传感器网络中的多查询进行优化，降低网络节点的能耗是本论文的研究重点。
Therefore, we focus on optimizing multiple queries energy efficiently to reduce energy consumption of sensor nodes. This thesis analyzes multiple queries in-network processing technologies in WSNs.
多连接查询优化；
多连接查询优化；
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