optimization. It has been extensively researched in database theory, and many algorithms were proposed for determining containment under different assumptions [@cnt1; @cnt2; @cnt3; @cnt4]. However, determining query containment analytically is not practically sufficient. Two queries may be analytically unrelated by containment, although, the execution result on a *specific* database of one query may actually be contained in the other. For example, consider the queries:\
Q1: *select \* from movies where title = ’Titanic’*\
Q2: *select \* from movies where release = 1997 and director = ’James Cameron’*\
Both queries execution results are identical since there is only one movie called Titanic that was released in 1997 and directed by James Cameron (he has not directed any other movie in 1997). Yet, using the analytic criterion, the queries are unrelated at all by containment.

To our knowledge, while query containment and equivalence have been well researched in past decades, determining the containment rate between two queries on a *specific* database, has not been considered by past research.

By definition, the containment rate of query $Q1$ in query $Q2$ on database $D$ is the percentage of rows in $Q1$’s execution result over $D$ that are also in $Q2$’s execution result over $D$. 