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Optimizing database query execution by extending the relational algebra to include non-standard join operators
Optimizing database query execution by extending the relational algebra to include non-standard join operators
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机译:通过扩展关系代数来优化数据库查询执行,以包括非标准加入运算符
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摘要
A method is executed at a computer system to retrieve data from a database. Upon receiving a database query, a database engine of the computer system parses the query to form an operator tree including a plurality of join operators. For each of the plurality of clauses, the database engine adds to the operator tree a respective node that specifies a mark join operator, a single join operator, an inner join operator, or an outer join operator. Specifically, the database engine adds the mark join operator when the respective clause includes one of a predetermined set of predicate subqueries, and adds the single join operator when the respective clause includes a scalar subquery. The database engine performs one or more optimization passes on the operator tree to form an optimized execution plan, and executes the optimized execution plan to retrieve a result set from the database.
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