Therefore, the database system performance tuning and optimization, involving multi-layers, are vital for the whole system to be in normal operation.

因此，基于数据库系统的性能调整与优化对于整个系统的正常运行起着至关重要的作用。

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As join operation to relational database, structural join order selection is at the heart of query optimization in an XML database.

和关系数据库中的连接运算一样，结构连接顺序的选择是XML数据库查询优化的核心。

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The optimization of database performance directly influences the efficient operation of the entire database application system.

数据库的性能优化直接影响到整个数据库应用系统的高效运行。

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