Sybase, Inc.

Roger D MacNicol

Steven A Kirk

David Walrath

Fang-Ying Yen

Jun Rao

Randall G Bello

Roland F McKenney

Katherine Tsouya Yang

Xiqing Li

A system, method, and computer program product for processing a database query are presented. Steps for identifying a table needed to resolve the query, creating an enumeration value, determining whether the enumeration value is semantically equivalent to data from a data field in the table, and using a temporary data structure to evaluate the query are disclosed.

Accelerating queries using delayed value projection of enumerated storage

A system, method, and computer program product for processing a database query are presented. Steps for creating a secondary enumeration when necessary and utilizing the secondary enumeration to improve query operations by processing enumeration values of the secondary enumeration instead of data represented by the enumeration values are disclosed.

Accelerating queries using secondary semantic column enumeration

An improved method for handling database queries including functional expressions against columns having enumerated storage is described. Upon receipt of a query including a predicate having at least one functional expression referencing at least one database column containing offsets to values in enumerated storage, a look-up table is created for storing results of evaluation of the predicate against the values in enumerated storage. Each functional expression of the predicate is evaluated against the values in enumerated storage and the results of evaluation are stored in the look-up table. Results stored in the look-up table may then be accessed through use of the offsets to values in enumerated storage. The method may also be utilized for projecting expressions against database columns having enumerated storage.

Database system providing methodology for acceleration of queries involving functional expressions against columns having enumerated storage

A database system providing improved methods for optimization and execution of queries aggregating information from multiple database tables is described. The improved method breaks serial operations into a group of child operations that can be individually optimized and processed in parallel. A query including a grouping operator over a union node is split by pushing the grouping operation down into each input arm of the union node. Specifically, grouping operators are inserted into each child arm of qualifying union nodes, enabling separate physical database tables to be summarized in parallel. Each of the child grouping operators concurrently groups data and generates summary results in parallel, taking advantage of capabilities of available parallel processing hardware. The aggregate operators of the original master grouping operator are modified to accept and correctly synthesize sub-aggregated results generated by each of the child grouping operators. The method also enables individual optimization of operations on each database table, including use of advantageous index-only execution plans.

Database system providing optimization of group by operator over a union all

Database system and methods are described for improving execution speed of database queries (e.g., for decision support) by optimizing execution of nested queries or &ldquo;subqueries,&rdquo; which are commonly used in client/server database environments. In particular, the basic approach employed is to recognize the part of the subquery that is not related to the outer references and cache the result of that part after its first execution. Later, the result can be reused and combined with the result of the rest of the subquery that is changing for each iteration. Methods are employed to recognize the invariant part of a data flow tree, and to restructure the evaluation plan to reuse the stored intermediate result. An efficient method is used to teach an existing join optimizer to understand the invariant feature and thus allow it to be able to generate better join plans in the new context. When query rewriting is not possible, therefore, the invariant technique provides significantly better performance than the traditional nested iteration method.

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Bedford, MA, United States of America

Roger D MacNicol