Testing Database Engines via Pivoted Query Synthesis [pdf]

I find really impressive the contrast between the simplicity of the approach and its effectiveness.

* The idea is to generate tests by picking a random row in a database and by crafting random queries which are expected to return that row.

* Sure the details are more complex, but this idea is really effective. The authors found 121 bugs in SQLite, MySQL, and Post-greSQL.

This is even amazing that a table with a single column and 3 rows can be used to detect a bug on SQLite, a so widely used database.