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2010
ACM

Capturing missing tuples and missing values

14 years 10 months ago
Capturing missing tuples and missing values
Databases in real life are often neither entirely closed-world nor entirely open-world. Indeed, databases in an enterprise are typically partially closed, in which a part of the data is constrained by master data that contains complete information about the enterprise in certain aspects [21]. It has been shown that despite missing tuples, such a database may turn out to have complete information for answering a query [9]. This paper studies partially closed databases from which both tuples and values may be missing. We specify such a database in terms of conditional tables constrained by master data, referred to as c-instances. We first propose three models to characterize whether a c-instance T is complete for a query Q relative to master data. That is, depending on how missing values in T are instantiated, the answer to Q in T remains unchanged when new tuples are added. We then investigate four problems, to determine (a) whether a given c-instance is complete for a query Q, (b) whe...
Wenfei Fan, Floris Geerts
Added 18 Oct 2010
Updated 18 Oct 2010
Type Conference
Year 2010
Where PODS
Authors Wenfei Fan, Floris Geerts
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