Download:
|
by Amy J. Lee, Andreas Koeller, Anisoara Nica, Elke A. Rundensteiner
In International Database Conference, Hong Kong
http://www.eecs.umich.edu/~anica/papers/IDC99-submit.ps
Add To MetaCart
Abstract:
Previous work in query rewriting has made the restricting assumption that the rewritten query must be equivalent to the initially given query. We now propose to relax this assumption to allow for query rewriting in situations where equivalent rewritings may not exist-- yet alternate not necessarily equivalent query rewritings may still be preferable to users over not receiving any answers at all. In this paper, we apply this concept of non-equivalent query rewriting to the problem of maintaining view definitions (data warehouses), where it now allows us to handle a much larger class of changes of the underlying information sources, namely not only data but also schema changes. This relaxed query notion allows for more diversity in acceptable query answers, but also raises a new issue of the evaluation of such queries. For this purpose, we introduce an analytical model of query rewritings that incorporates measures of information preservation (quality) of a query in addition to the commonly studied measures of view maintenance performance (query cost). Quality is modeled as a function of the divergence from the intended view extent, both in terms of the preservation of the information amount and the information type. Both quality and cost are integrated into one uniform model, called the Quality-CostModel or QC-Model, to allow for a trade-off among these two measures. This model can be used to compare two alternate (even if not equivalent) rewritings, and thus to automatically select a good view maintenance solution from among numerous non-equivalent rewritings. We also report on an experimental evaluation of our
Citations
|
389
|
Answering queries using views
– Levy, Mendelzon, et al.
- 1995
|
|
234
|
Maintaining Views Incrementally
– Gupta, Mumick, et al.
- 1993
|
|
230
|
View maintenance in a warehousing environment
– Zhuge, Garcia-Molina, et al.
- 1995
|
|
220
|
Maintenance of materialized views: Problems, techniques, and applications
– GUPTA, MUMICK
- 1995
|
|
216
|
Optimizing queries with materialized views
– Chaudhuri, Krishnamurthy, et al.
- 1995
|
|
176
|
Query optimization in database systems
– Jarke, Koch
- 1984
|
|
170
|
Wm.; Efficiently Updating Materialized Views
– Blakeley, Larson, et al.
- 1986
|
|
134
|
Representing and using interschema knowledge in cooperative information systems
– Catarci, Lenzerini
- 1993
|
|
88
|
Efficient View Maintenance at Data Warehouses
– Agrawal, Abbadi, et al.
- 1997
|
|
86
|
The Strobe Algorithms for Multi-Source Warehouse Consistency
– Zhuge, Garc'ia-Molina, et al.
- 1996
|
|
83
|
Data Integration using Self-Maintainable Views
– Gupta, Jagadish, et al.
- 1994
|
|
59
|
A critical investigation of recall and precision as measures of retrieval system performance
– Raghavan, Jung, et al.
- 1989
|
|
58
|
Answering queries with aggregation using views
– Srivastava, Dar, et al.
- 1996
|
|
49
|
Answering queries using limited external processors
– Levy, Rajaraman, et al.
- 1996
|
|
46
|
On-line warehouse view maintenance
– Quass, Widom
- 1997
|
|
34
|
The CVS Algorithm for View Synchronization in Evolvable Large-Scale Information Systems
– Nica, Lee, et al.
- 1998
|
|
31
|
On Preserving views in evolving environments
– Rundensteiner, Lee, et al.
- 1997
|
|
31
|
Multiple View Consistence for Data Warehousing
– Zhuge, Wiener, et al.
- 1997
|
|
25
|
Keeping Virtual Information Resources Up and Running
– Lee, Nica, et al.
- 1997
|
|
22
|
View Maintenance after View Synchronization
– Nica, Rundensteiner
- 1999
|
|
18
|
Data Warehouse Evolution: Trade-offs between Quality and Cost of Query Rewritings
– Lee, Koeller, et al.
- 1999
|
|
11
|
Using Containment Information for View Evolution in Dynamic Distributed Environments
– Nica, Rundensteiner
- 1998
|
|
8
|
The EVE Framework: View Synchronization in Evolving Environments
– Lee, Nica, et al.
- 1997
|
|
8
|
On Translating Loosely-Specified Queries into Executable Plans in Large-Scale Information Systems
– Nica, Rundensteiner
- 1997
|
|
6
|
An Attribute Based Model for Database Access Cost Analysis
– Yao
- 1977
|
|
5
|
An Analysis of a Dynamic Query Optimization Schema for Different Data Distributions
– Berg, Kersten
- 1994
|
|
2
|
Knowledge Based Schema Integration in a Heterogeneous Environment
– Catarci, Santucci, et al.
- 1993
|
