NDLI: Reverse data exchange: Coping with nulls

Content Provider	ACM Digital Library
Author	Tan, Wang-Chiew Popa, Lucian Fagin, Ronald Kolaitis, Phokion G.
Copyright Year	2011
Abstract	An inverse of a schema mapping $\textit{M}$ is intended to undo what $\textit{M}$ does, thus providing a way to perform reverse data exchange. In recent years, three different formalizations of this concept have been introduced and studied, namely the notions of an inverse of a schema mapping, a quasi-inverse of a schema mapping, and a maximum recovery of a schema mapping. The study of these notions has been carried out in the context in which source instances are restricted to consist entirely of constants, while target instances may contain both constants and labeled nulls. This restriction on source instances is crucial for obtaining some of the main technical results about these three notions, but, at the same time, limits their usefulness, since reverse data exchange naturally leads to source instances that may contain both constants and labeled nulls. We develop a new framework for reverse data exchange that supports source instances that may contain nulls, and we thereby overcome the semantic mismatch between source and target instances of the previous formalizations. The development of this new framework requires a careful reformulation of all the important notions, including the notions of the identity schema mapping, inverse, and maximum recovery. To this effect, we introduce the notions of extended identity schema mapping, extended inverse, and maximum extended recovery, by making systematic use of the homomorphism relation on instances. We give results concerning the existence of extended inverses and of maximum extended recoveries, and results concerning their applications to reverse data exchange and query answering. Moreover, we show that maximum extended recoveries can be used to capture in a quantitative way, the amount of information loss embodied in a schema mapping specified by source-to-target tuple-generating dependencies.
Starting Page	1
Ending Page	42
Page Count	42
File Format	PDF
ISSN	03625915
e-ISSN	15574644
DOI	10.1145/1966385.1966389
Volume Number	36
Issue Number	2
Journal	ACM Transactions on Database Systems (TODS)
Language	English
Publisher	Association for Computing Machinery (ACM)
Publisher Date	2011-06-02
Publisher Place	New York
Access Restriction	One Nation One Subscription (ONOS)
Subject Keyword	Schema mapping Chase Data exchange Data integration Inverse Maximum recovery Model management Quasi-inverse
Content Type	Text
Resource Type	Article
Subject	Information Systems

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

Reverse data exchange: coping with nulls

Quasi-inverses of schema mappings

The recovery of a schema mapping: Bringing exchanged data back

Inverting schema mappings

Quasi-inverses of schema mappings

Reverse Data Exchange: Coping with Nulls (2009)

Reverse data exchange: Coping with nulls (2009)

The structure of inverses in schema mappings

The recovery of a schema mapping: bringing exchanged data back

Reverse data exchange: Coping with nulls

Similar Documents

Reverse data exchange: coping with nulls

Quasi-inverses of schema mappings

The recovery of a schema mapping: Bringing exchanged data back

Inverting schema mappings

Quasi-inverses of schema mappings

Reverse Data Exchange: Coping with Nulls (2009)

Reverse data exchange: Coping with nulls (2009)

The structure of inverses in schema mappings

The recovery of a schema mapping: bringing exchanged data back

Reverse data exchange: Coping with nulls