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.
多连接查询优化；
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.
如果查询中有属于多列索引的连接列或过滤列，则使用UPDATESTATISTICSHIGH。
Use UPDATE STATISTICS HIGH if queries have a multi-column indexed defined on join columns or filter columns.
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.
结构化连接是XML查询处理的核心操作，目前已经提出了许多结构化连接的算法，但都不支持多版本的XML文档。
Structural join is the core operation in XML query processing, there have been a number of algorithms proposed for structural join, but all of them could not support query of multiple versions XML.
为了提高查询处理器的执行效率，采用启发式规则来搜索最优的多连接表达式并行调度执行计划。
To improve the execution efficiency of the query processors, the authors exploit heuristics to seek the optimum parallel scheduling execution plan for multi-join expressions.
为了提高查询处理器的执行效率，采用启发式规则来搜索最优的多连接表达式并行调度执行计划。
To improve the execution efficiency of the query processors, the authors exploit heuristics to seek the optimum parallel scheduling execution plan for multi-join expressions.
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