When doing some comparisons of query optimization in Microsoft SQL Server and MariaDB I noticed that there is a second type of table elimination which MariaDB has not yet implemented. It depends on foreign keys being declared, and can under some circumstances substantially improve performance. Rather than to write a lengthy discussion, here is a test script for MariaDB 5.2.5 in which the queries with the condition "where ... is not null" should result in this type of table elimination: http://pastebin.com/s68RwgG2 This screencast shows the table elimination in effect in MSSQL: http://www.screenr.com/tPG We rely on table elimination to get better performance in 3NF-views and functions used in our Anchor Modeling (6NF-table) technique. However, the need for table elimination has previously come from denormalized modeling, where it is used to speed up queries against star schemas (e g eliminating dimension tables). It should therefore not only be appreciated by our crowd, if implemented in full. We were very happy to see the 'outer join table elimination' implemented and are wondering if someone could put in the effort to add the 'foreign key table elimination'? Since everything we do with Anchor Modeling is Open Source, it would be nice to have an Open Source database that fully supports the technique. Support in other databases is described here, if anyone is interested: http://www.anchormodeling.com/?page_id=22 Thanks, Lars