Affiliation:
1. University of California at San Diego
2. IBM Almaden Research Center
3. University of Pennsylvania
Abstract
Let Σ
1
, Σ
2
be two schemas, which may overlap,
C
be a set of constraints on the joint schema Σ
1
∪ Σ
2
, and
q
1
be a Σ
1
-query. An
(equivalent) reformulation
of
q
1
in the presence of
C
is a Σ
2
-query,
q
2
, such that
q
2
gives the same answers as
q
1
on any Σ
1
∪ Σ
2
-database instance that satisfies
C
. In general, there may exist multiple such reformulations and choosing among them may require, for example, a cost model.
Publisher
Association for Computing Machinery (ACM)
Subject
Information Systems,Software
Cited by
73 articles.
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