Titre de dissertation: Computing Range Consistent Answers to Conjunctive Queries with Aggregation

Promoteur: Monsieur Jef Wijsen

Résumé de la dissertation: This thesis focuses on the problem of answering numerical queries issued against databases that may violate primary key constraints. A database repair is defined as any maximal subset of the original database that satisfies all constraints. The range consistent answer to a numerical query is a pair [glb, lub], where glb and lub denote the greatest lower bound and least upper bound, respectively, of the query results across all possible repairs. This work studies the computational complexity of determining range consistent answers to conjunctive queries with aggregation. In SQL, such queries follow the SELECT-FROM-WHERE-GROUP BY format, where the WHERE clause consists of a conjunction of equalities, and the SELECT clause may include aggregate functions such as MAX, MIN, SUM, AVG, or COUNT. The thesis investigates sufficient and necessary syntactic conditions under which range consistent answers can be computed via rewriting into first-order aggregate logic.