US 10,885,034 B2Granted

Data query method and apparatus, and database system

AssigneeHuawei Technologies Co., Ltd.

InventorsGuoping Wang, Junhua Zhu

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Abstract

A data query method and apparatus, and a database system, where the method includes receiving a data query request, generating an original query plan according to the data query request, obtaining a candidate query plan set according to the original query plan, restructuring a join predicate in the original query plan, determining basic information of a restructured join predicate in the original query plan, determining a constraint condition of the restructured join predicate in the original query plan, determining an equal-cost query plan for the original query plan according to the basic information of the restructured join predicate in the original query plan and the constraint condition of the restructured join predicate in the original query plan, and performing querying according to the equal-cost query plan for the original query plan. Hence, data query performance can be improved.

Claims20

Dependent claims

A data query method, executed by a database management system managing a database, comprising:

receiving a data query request from a client, wherein the database management system and the database run on a computer device, and wherein the computer device is coupled with the client by a network;
generating an original query plan according to the data query request;
restructuring a join predicate in the original query plan by:
transforming all join predicates of an inner join operation in the original query plan into a conjunctive form;
combining join predicates having a same input table;
and
combining all join predicates of a non-inner join operation in the original query plan into the join predicate;
determining basic information of a restructured join predicate in the original query plan;
determining, based on a join operation rule, a constraint condition of the restructured join predicate in the original query plan;
determining an equal-cost query plan for the original query plan according to the basic information of the restructured join predicate in the original query plan and the constraint condition of the restructured join predicate in the original query plan;
performing querying in the database, according to the equal-cost query plan for the original query plan, to generate a querying result;
and
sending the querying result to the client.

10 more elements

A data query apparatus, coupled with a client by a network, the data query apparatus comprising:

a memory storing a plurality of instructions;
and
a processor coupled to the memory, wherein the instructions cause the processor to be configured to:
receive a data query request from the client;
generate an original query plan according to the data query request;
restructure a join predicate in the original query plan by:
transforming all join predicates of an inner join operation in the original query plan into a conjunctive form;
combining join predicates having a same input table;
and
combining all join predicates of a non-inner join operation in the original query plan into the join predicate;
determine basic information of a restructured join predicate in the original query plan;
determine, based on a join operation rule, a constraint condition of the restructured join predicate in the original query plan;
determine an equal-cost query plan for the original query plan according to the basic information of the restructured join predicate in the original query plan and the constraint condition of the restructured join predicate in the original query plan;
perform querying in a database, according to the equal-cost query plan for the original query plan, to generate a querying result;
and
send the querying result to the client.

13 more elements

A database system, comprising:

a database;
and
a data query apparatus coupled to the database and comprising;
a memory storing a plurality of instructions;
and
a processor coupled to the memory, wherein the instructions cause the processor to be configured to:
receive a data query request;
generate an original query plan according to the data query request;
restructure a join predicate in the original query plan by:
transforming all join predicates of an inner join operation in the original query plan into a conjunctive form;
combining join predicates having a same input table;
and
combining all join predicates of a non-inner join operation in the original query plan into the join predicate;
determine basic information of a restructured join predicate in the original query plan;
determine, based on a join operation rule, a constraint condition of the restructured join predicate in the original query plan;
determine an equal-cost query plan for the original query plan according to the basic information of the restructured join predicate in the original query plan and the constraint condition of the restructured join predicate in the original query plan;
and
perform querying according to the equal-cost query plan for the original query plan.

15 more elements

Dependencies are inferred from the claim text.