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    • 3. 发明授权
    • Outerjoin and antijoin reordering using extended eligibility lists
    • 使用扩展资格清单进行外联和反连接重新排序
    • US06665663B2
    • 2003-12-16
    • US09809846
    • 2001-03-15
    • Bruce Gilbert LindsayGuy Maring LohmanMir Hamid PiraheshJun Rao
    • Bruce Gilbert LindsayGuy Maring LohmanMir Hamid PiraheshJun Rao
    • G06F1730
    • G06F17/30466G06F17/30469Y10S707/99934
    • An optimization technique that reorders outerjoins and antijoins with inner joins in a bottom-up optimizer of a relational database management system (RDBMS). Each join predicate is associated with a normal eligibility list (NEL) that includes tables that are referenced in the join predicate and an extended eligibility list (EEL) that includes additional tables that are referenced in conflicting join predicates. An EEL includes all the tables needed by a predicate to preserve the semantics of the original query. During join enumeration, the optimizer determines whether a join predicate's EEL is a subset of all the tables in two subplans to be merged, i.e., whose EEL is covered. If so, the two subplans are combined using the join predicate. Otherwise, the two subplans cannot be joined. Two approaches are used to reordering: without compensation and with compensation. The “without compensation” approach only allows join reorderings that are valid under associative rules. Thus, the optimizer will not combine subplans using a join predicate whose EEL is not covered. The “with compensation” approach allows two subplans to be combined using the join predicate, when a join predicate's EEL is not covered, as long as the join predicate's NEL is covered. Compensation is performed through nullification and best match. Multiple compensations may be merged and performed at any time.
    • 在关系数据库管理系统(RDBMS)的自下而上优化器中,通过内部联接重新排列外部联结和反联合的优化技术。每个连接谓词与正常资格列表(NEL)相关联,包括在连接谓词中引用的表 以及扩展资格列表(EEL),其中包括在冲突的连接谓词中引用的其他表。 EEL包括谓词所需的所有表,以保留原始查询的语义。 在连接枚举期间,优化器确定连接谓词的EEL是否是要合并的两个子计划中的所有表的子集,即其EEL被覆盖。 如果是这样,则使用连接谓词组合两个子计划。 否则,两个子计划不能加入。 两种方法用于重新排序:无补偿和补偿。 “无补偿”方法仅允许在关联规则下有效的连接重排序。 因此,优化器不会使用不包括EEL的连接谓词来组合子计划。 只要连接谓词的NEL被覆盖,“附加补偿”方法允许使用连接谓词组合两个子计划,当连接谓词的EEL不被覆盖时。 赔偿通过无效和最佳匹配执行。 可以随时合并和执行多重补偿。
    • 8. 发明授权
    • Efficient processing of queries in federated database systems
    • 联合数据库系统中查询的高效处理
    • US08538985B2
    • 2013-09-17
    • US12046273
    • 2008-03-11
    • Anjali Betawadkar-NorwoodHamid PiraheshDavid Everett Simmen
    • Anjali Betawadkar-NorwoodHamid PiraheshDavid Everett Simmen
    • G06F17/30
    • G06F17/30545
    • Methods and apparatus, including computer program products, implementing and using techniques for processing a federated query in a federated database system. A federated query is received at a federated database server. A federated query execution plan is generated based on the received federated query. The federated query execution plan defines one or more source servers of the federated database and a unique subquery to be executed on each of the source servers. The subqueries are distributed to the source servers in accordance with the federated query execution plan. The respective subqueries are executed asynchronously at the source servers. The subquery results are passed to a first designated source server defined in the federated query execution plan. The subquery results are joined and aggregated at the first designated source server into a final query result. The final query result is returned to the federated database server.
    • 方法和装置,包括计算机程序产品,在联合数据库系统中处理联合查询的实现和使用技术。 在联合数据库服务器处接收联合查询。 基于接收的联合查询生成联合查询执行计划。 联合查询执行计划定义联合数据库的一个或多个源服务器和要在每个源服务器上执行的唯一子查询。 根据联合查询执行计划,子查询分发到源服务器。 相应的子查询在源服务器上异步执行。 子查询结果被传递到联合查询执行计划中定义的第一个指定的源服务器。 子查询结果在第一个指定的源服务器上加入并聚合成最终的查询结果。 最终查询结果返回到联合数据库服务器。