Complexity and Approximation of Fixing Numerical Attributes in Databases Under Integrity Constraints

Details Complexity and Approximation of Fixing Numerical Attributes in Databases Under Integrity Constraints Complexity and Approximation of Fixing Numerical Attributes in Databases Under Integrity Constraints

2005-03-15

arxiv.org/abs/cs/0503032v3

Computer Science

Databases

35 pages. Extended version of the camera ready version to appear in Proc. of the Databases Programming Languages Conference (D

Scientific paper

Consistent query answering is the problem of computing the answers from a database that are consistent with respect to certain integrity constraints that the database as a whole may fail to satisfy. Those answers are characterized as those that are invariant under minimal forms of restoring the consistency of the database. In this context, we study the problem of repairing databases by fixing integer numerical values at the attribute level with respect to denial and aggregation constraints. We introduce a quantitative definition of database fix, and investigate the complexity of several decision and optimization problems, including DFP, i.e. the existence of fixes within a given distance from the original instance, and CQA, i.e. deciding consistency of answers to aggregate conjunctive queries under different semantics. We provide sharp complexity bounds, identify relevant tractable cases; and introduce approximation algorithms for some of those that are intractable. More specifically, we obtain results like undecidability of existence of fixes for aggregation constraints; MAXSNP-hardness of DFP, but a good approximation algorithm for a relevant special case; and intractability but good approximation for CQA for aggregate queries for one database atom denials (plus built-ins).

Affiliated with

Also associated with

No associations

Rating

Complexity and Approximation of Fixing Numerical Attributes in Databases Under Integrity Constraints does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Complexity and Approximation of Fixing Numerical Attributes in Databases Under Integrity Constraints, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Complexity and Approximation of Fixing Numerical Attributes in Databases Under Integrity Constraints will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-316228