DATA QUERY METHOD AND APPARATUS, AND DATABASE SYSTEM
A data query method and apparatus, and a database system are provided. The method includes: receiving a data query request (S110); generating an original query plan according to the data query request (S1120); obtaining a candidate query plan set according to the original query plan (S1130); restructuring a join predicate in the original query plan (S1140); determining basic information of a restructured join predicate in the original query plan (S1150); determining a constraint condition of the restructured join predicate in the original query plan (S1160); 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 (S1170); and performing querying according to the equal-cost query plan for the original query plan (S1180). According to the data query method and apparatus, and the database system, data query performance can be improved.