Online analytical processing (OLAP) is a core functionality in database systems. The
performance of OLAP is crucial to make online decisions in many applications. However, it is …

We study the complexity of enumerating the answers of Conjunctive Queries (CQs) in the
presence of Functional Dependencies (FDs). Our focus is on the ability to list output tuples …

Parallel join algorithms have received much attention in recent years due to the rapid
development of massively parallel systems such as MapReduce and Spark. In the database …

This position paper provides an overview of our recent advances in the study of big graphs,
from theory to systems to applications. We introduce a theory of bounded evaluability, to …

Query with aggregates is one of the most important classes of ad-hoc queries. Since query
response time is critical in many scenarios, small errors are usually tolerable for query …

Big data introduces challenges to query answering, from theory to practice. A number of
questions arise. What queries are" tractable" on big data? How can we make big data" …

It is cost-prohibitive to find matches Q (G) of a pattern query Q in a big graph G. We approach
this by fetching a small subgraph GQ of G such that Q (GQ)= Q (G). We show that many …

The view propagation problem is a class of view update problem in relational databases [7],
involving deletion and insertion propagations. Given source database D, conjunctive query …

Recent works on bounding the output size of a conjunctive query with functional
dependencies and degree constraints have shown a deep connection between fundamental …

A mechanism for rewriting a bounded query onto a view is disclosed. A query, access
constraints, and cached view (s) are obtained. The cached view (s) contain results of the …