所以大多数研究分布式查询优化以减少通讯开销为目标。
So most research of distributed query optimization aim at reducing communication cost.
在分布式查询优化中，应同时考虑本地处理代价和传输代价。
In the distributed query optimization, both local processing cost and transmission cost should be thought over simultaneously.
要改进性能，联合需要经常使用缓存、物理查询表(MQT)以及分布式查询优化和执行。
To improve performance, federation frequently USES caching, materialized query tables (MQTs), and distributed query optimization and execution.
并用实例证明其相对于没有进行分布式查询优化的算法可以大大减少网络上传输的数据量。
The method of distributed query optimization is analyzed deeply which use semi-join algorithm and query tree disassembling.
为了解决那个问题，OODT提供了对分布式资源的透明访问、数据恢复和查询优化功能以及分布式处理和虚拟存档。
To solve that problem, OODT provides transparent access to distributed resources, functionality for data discovery and query optimization, as well as distributed processing and virtual archives.
分布式数据查询是分布式数据库管理系统的核心，而查询优化算法又是查询处理中的关键技术。
The distributed data query is the core of the distributed database managing system, but the optimized query algorithm is the key technology in query processing.
尽管在分布式处理中也使用某些集中式查询处理中的技术和方法，但就其问题的规模和优化的因素，都与集中式查询处理有质的不同。
Although some technique and ways to query in centralized database system can also be used in distributed one, there are basic differences between them in terms of scale and factors of databases.
本文描述一个分布式关系数据库系统中具有语义优化的查询处理算法。
In this paper, we describe an algorithm, for query processing with semantic optimization in distributed relational database systems.
分布式综合查询调度和优化技术研究。
Researching of distributed interoperable query scheduling and optimizing technology.
分布式数据查询是分布式数据库管理系统的核心，而查询优化算法又是查询处理中的关键技术。
The distribute data query is the core of the distribute database manages system, but the optimized query algorithm is the key technology in query the processed.
查询优化：分布式数据集成系统查询优化的目标与集中式数据库有所不同。
Query optimization: the goals of query optimization in distributed data integration system are different from those in traditional database system.
在分布式查询处理中，要根据不同的优化目的来设计各种查询处理的优化算法。
In Distrabuted query, we should devise the query optimization algorithm according to different optimization purpose.
在分布式查询处理中，要根据不同的优化目的来设计各种查询处理的优化算法。
In Distrabuted query, we should devise the query optimization algorithm according to different optimization purpose.
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