Huawei Technologies Co., Limited

Future Wei Technologies, Inc.

Ahmad Ghazal

Yang Sun

Ron-Chung Hu

Mingyi Zhang

Jianjun Chen

Sofoklis Floratos

Xiaodong Zhang

A method for functionally rewriting iterative queries for a relational database management system (RDBMS) is provided. The method comprises receiving a first iterative query, the first iterative query having a first non-iterative part that defines a first main table and a first iterative part that generates values in rows of a first working table based on values in rows of the first main table, determining that the first iterative part modifies all of the rows of the first working table, and rewriting the first iterative part, including: adding a renaming operation to rename the first working table to a new first main table and to rename the first main table to a new first working table, adding a first Delete operation to delete each row of the new first working table, and adding a first loop operation to repeat the first iterative part until a first termination condition is met.

Processing iterative query constructs in relational databases

A query processing device includes a communication interface accessing a database and database catalog, a memory storing instructions, and a processor coupled to the memory and the communication interface. The processor executes the instructions to parse a query and generate first and second execution plans for the query, retrieve respective previously determined cardinality values for previously executed logical steps of the first and second execution plans from the database catalog, select an execution plan from the first execution plan or the second execution plan, the selected execution plan having a lower cost based on the previously determined cardinality values, and execute the selected execution plan on data accessed from the database. The query processing system stores actual cardinality values determined during the execution of the logical steps in the database catalog for use by subsequent queries. The query processing device, therefore, re-uses previously determined cardinality values.

Query processing using logical query steps having canonical forms

Growing community of inventors

Redondo Beach, CA, United States of America

Ahmad Ghazal