1. A method comprising: receiving a query; determining that the query includes an inner join between a parent table and a child table; determining 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; determining that the query does not access any attribute in the parent table other than the pk; determining that the query specifies an equality predicate of the form pk=fk; determining that the query selects a snapshot from the parent using a predicate of the form parent.[period attribute] contains a point in time (t 1 ); determining that the query selects from the child those rows whose TRC-attribute is equal to or prior to t 1 ; eliminating the inner join when planning execution of the query; executing the query to produce a result; and saving the result.