Eliminating inner joins based on a contained predicate and a temporal relationship constraint

摘要

A query is received. It is determined that the query includes an inner join between a parent table and a child table. It is determined that the following relationships exist between the parent table and the child table: referential integrity (“RI”) between a primary key attribute (pk) in the parent table and a foreign key attribute (fk) in the child table, where“attribute”is defined to mean one or more columns; and a temporal relationship constraint (“TRC”) between a period attribute in the parent table and a TRC-attribute in the child table, the TRC-attribute being a date or time attribute. It is determined that the query does not access any attribute in the parent table other than the pk. It is determined that the query specifies an equality predicate of the form pk=fk. It is determined that the query specifies a condition that requires the TRC-attribute value to be contained in the parent table's period attribute duration. It is determined that the query contains no other qualification conditions on the parent table's period attribute. The inner join is eliminated when planning execution of the query. The query is executed to produce a result. The result is saved.