The field of database query processing and optimization is moving towards addressing long-standing open questions and developing innovative solutions to complex problems. Researchers are exploring new approaches to query containment, semantic query metrics, and responsibility measures for query answers. Notably, recent work has focused on the decidability of query containment problems for bag semantics and the feasibility of defining semantic query metrics. Additionally, there is a growing interest in developing frameworks for cleaning operational databases and proposing new responsibility measures that are tractable and satisfy intuitive properties.

Some noteworthy papers in this area include: RED2Hunt, which proposes a human-in-the-loop framework for identifying and cleaning hidden redundancy in relational databases implemented with surrogate keys. Shapley Revisited, which introduces a new family of responsibility measures that are tractable and satisfy intuitive properties, and are equivalent to the Shapley value of a suitably defined cooperative game.