公开(公告)号：US20220004551A1

公开(公告)日：2022-01-06

申请号：US17446679

申请日：2021-09-01

Applicant: Futurewei Technologies, Inc.

Inventor： Ahmad Ghazal ,  Ron-Chung Hu ,  Mingyi Zhang

IPC: G06F16/242 ,  G06F16/2455 ,  G06F16/22

Abstract: 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.

公开(公告)号：US11940997B2

公开(公告)日：2024-03-26

申请号：US17446679

申请日：2021-09-01

Applicant: Futurewei Technologies, Inc.

Inventor： Ahmad Ghazal ,  Ron-Chung Hu ,  Mingyi Zhang

IPC: G06F16/24 ,  G06F16/22 ,  G06F16/242 ,  G06F16/2455

CPC classification number: G06F16/2433 ,  G06F16/2255 ,  G06F16/2455

Abstract: 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.

公开(公告)号：US20180336262A1

公开(公告)日：2018-11-22

申请号：US15600639

申请日：2017-05-19

Applicant: Futurewei Technologies, Inc.

Inventor： Ahmad Ghazal

IPC: G06F17/30

Abstract: The disclosure relates to technology for estimating selectivity of non-join multi-column (NJMC) predicates of multi-column table (MCT) database queries is disclosed. The selectivity may be geometrically estimated by representing the full space of the MCT as one polyhedron having at least one dimension for each column of the MCT, and representing the NJMC predicate space as another polyhedron having at least one dimension for each column of a predicate space determined by applying the NJMC predicate to the MCT. Then the selectivity of the NJMC predicate may be estimated by computing a percentage of the size of the NJMC predicate space polyhedron to the size of the full space polyhedron. This more accurate estimate helps database query optimizers produce better query execution plans that utilize system resources more efficiently.