Mining all frequent projection-selection queries from a relational table

In this paper we study the problem of mining all frequent queries in a given database table, a problem known to be intractable even for conjunctive queries. We restrict our attention to projection-selection queries, and we assume that the table to be mined satisfies a set of functional dependencies. Under these assumptions we define a pre-ordering over queries and we show the following: (a) the support measure is anti-monotonic (with respect to ), and (b) if we define q q iff q q and q q then all queries of an equivalence class have the same support. With these results at hand, we further restrict our attention to star schemas of data warehouses. In those schemas, the set of functional dependencies satisfies an important property, namely, the union of keys of all dimension tables is a key for the fact table. The main contribution of this paper is the proposal of a level-wise algorithm for mining all frequent projection-selection queries in a data warehouse over a star schema. Moreove...

• Type: Conference
• Year: 2008
• Where: EDBT
• Authors: Tao-Yuan Jen, Dominique Laurent, Nicolas Spyratos
• Keywords: Conjunctive Queries, Database, EDBT 2008, Frequent Projection-selection Queries, Frequent Queries