[mrigger]

We automatically generate databases and queries. The main challenge is to verify that the query yields the expected result. To this end, we have designed and implemented three different approaches:

* Pivoted Query Synthesis (PQS): The main idea is to generate a query that is guaranteed to fetch a randomly-selected row, to which we refer as the pivot row. If the pivot row is not contained in the result set, we have detected a bug.

* Non-Optimizing Reference Engine Construction (NoREC): The idea is to transform a query so that it cannot be optimized effectively by the DBMS. By comparing the result set of the "optimized" query with the result set of the "unoptimized" query, we can detect bugs that affect the DBMS' query optimizer.

* Ternary Logic Partitioning (TLP): The main idea of this approach is that we can partition a given query into multiple "partitioning" queries, each of which computes a partition of the result, and to then combine these partitions to derive the same result as the original query. If the two results differ, we have detected a bug in the DBMS.