Like other relational database management systems such as Oracle and SQL Server, Informix has its internal optimizer, which is responsible for selecting the best query execution plan.

与Oracle和SQL Server等其他关系数据库管理系统一样，Informix也有内部优化器，负责选择最佳的查询执行计划。

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Using XQuery (a functional language designed to query collections of XML data) with native XML database systems can be extremely useful in some situations.

在某些情况下，在原生 XML 数据库系统中使用 XQuery（一种用于查询 XML 数据集合的函数型语言）可能非常有用。

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For the distributed database systems, query processing becomes more difficult because of distribution and redundance of data.

在分布式数据库系统中，由于数据的分布和冗余，查询处理变得更为复杂。

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This traditional database platforms, known as relational database management systems (RDBMS) all use a language called SQL (structured query language).

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