Cost-based optimization in DB2 XML
Cost-based optimization in DB2 XML
复制标题
DB2 XML 中基于成本的优化
DOI：
10.1147/sj.452.0299
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
Chun Zhang
中科院分区：
文献类型：
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作者：
Andrey Balmin;Tom Eliaz;J. Hornibrook;Lipyeow Lim;G. Lohman;David E. Simmen;Min Wang;Chun Zhang
DB2 XML是一种混合数据库系统，它结合了DB2 Universal DatabaseTM （UDB）的关系功能和全面的原生XML支持。DB2 XML增强了DB2®UDB，为XQuery和SQL/XML提供了原生XML存储、XML索引和查询处理功能，这些功能与SQL的功能集成在一起。本文介绍了对DB2 UDB编译器（尤其是其基于成本的查询优化器）所做的扩展，以支持XQuery和SQL/XML查询，其中使用了为SQL查询的关系数据开发的许多相同基础结构。它描述了支持XQuery和SQL/XML的关系基础设施所面临的挑战，并提供了对优化器的三个主要部分进行扩展的基本原理：计划操作符、基数和成本模型以及统计信息收集。
DB2 XML is a hybrid database system that combines the relational capabilities of DB2 Universal DatabaseTM (UDB) with comprehensive native XML support. DB2 XML augments DB2® UDB with a native XML store, XML indexes, and query processing capabilities for both XQuery and SQL/XML that are integrated with those of SQL. This paper presents the extensions made to the DB2 UDB compiler, and especially its cost-based query optimizer, to support XQuery and SQL/XML queries, using much of the same infrastructure developed for relational data queried by SQL. It describes the challenses to the relational infrastructure that supporting XQuery and SQL/XML poses and provides the rationale for the extensions that were made to the three main parts of the optimizer: the plan operators, the cardinality and cost model, and statistics collection.