Causality in Databases

Provenance is often used to validate data, by verifying its origin and explaining its derivation. When searching for \causes" of tuples in the query results or in general observations, the analysis of lineage becomes an essential tool for providing such justications. However, lineage can quickly grow very large, limiting its immediate use for providing intuitive explanations to the user. The formal notion of causality is a more rened concept that identies causes for observations based on user-dened criteria, and that assigns to them gradual degrees of responsibility based on their respective contributions. In this paper, we initiate a discussion on causality in databases, give some simple denitions, and motivate this formalism through a number of example applications.