Middleware-based Database Replication: The Gaps between Theory and Practice

Database replication is difficult but indispensable. We report on our experiences building and deploying middleware-based replication systems both as commercial products and research systems. We identify gaps that still separate academic research from industrial practice and thus thwart potential technology transfer from academia to the field. We structure our analysis along three axes -- performance, availability and management -- and outline unmet database replication challenges at several levels. We hope to both motivate and aid researchers in bridging these gaps between theory and practice. We sift through the last decade of open-source, academic, and commercial database replication systems and combine this material with case studies resulting from developing and deploying real systems at many customer sites. We propose two agendas, one for academic research and one for industrial R&D, which we expect can bridge the gaps within 5-10 years.