Lossless Selection Views under Conditional Domain Constraints

Abstract

Abstract-A set of views defined by selection queries splits a database relation into sub-relations, each containing a subset of the original rows. This decomposition into horizontal fragments is lossless when the initial relation can be reconstructed from the fragments by union. In this paper, we consider horizontal decomposition in a setting where some of the attributes in the database schema are interpreted over a specific domain, on which a set of special predicates and functions is defined. We study losslessness in the presence of integrity constraints on the database schema. We consider the class of conditional domain constraints (CDCs), which restrict the values that the interpreted attributes may take whenever a certain condition holds on the noninterpreted ones, and investigate lossless horizontal decomposition under CDCs in isolation, as well as in combination with functional and unary inclusion dependencies.

Virtual Knowledge Graphs: An Overview of Systems and Use Cases

“…This will allow also data and content producers to decouple from the low-level details of the storage structure and organization. A technical challenge for updates in VKGs is the need to address the notoriously difficult view-update problem [69], which could be overcome by relying on business knowledge and constraints over the data.…”