Schema Evolution publication categorizer

An increasing number of databases are becoming Web accessible through form-based search interfaces, and

Bancilhon and Spyratos [l] show how the choice of a complementary view will
select a view update translator. They claim that “User requirements impose [the
constraint that] . . . (ii) The user must have the means to cancel, if he wishes,
the effect of every update that he is allowed on the view.” (p. 562) If this
requirement is eliminated, there are other reasonable translations that become
acceptable. We present a particular view update translator that is quite reasonable,
but that does not preserve any complement, and for which the requirement
does not hold.

In this article, we develop a relational algebra for metadata integration, Federated Interoperable Relational Algebra (FIRA). FIRA has many desirable properties such as compositionality, closure, a deterministic semantics, a modest complexity, support for nested queries, a subalgebra equivalent to canonical Relational Algebra (RA), and robustness under certain classes of schema evolution.

Views as a means to describe parts of a given data collection play an important role in many database applications. In dynamic environments where data is updated, not only information provided by views, but also information provided by data sources yet missing from views turns out to be relevant: Previously, this missing information has been characterized in terms of view complements; recently, it has been shown that view complements can be exploited in the context of data warehouses to guarantee desirable warehouse properties such as independence and self-maintainability.

A schema mapping is a specification that describes how data structured under one schema (the
source schema) is to be transformed into data structured under a different schema (the target
schema). A fundamental problem is composing schema mappings: given two successive schema
mappings, derive a schema mapping between the source schema of the first and the target schema
of the second that has the same effect as applying successively the two schema mappings.
In this paper, we give a rigorous semantics to the composition of schema mappings and investigate

The introduction of the Semantic Web vision and
the shift toward machine understandable Web resources has
unearthed the importance of automatic semantic reconciliation.
Consequently , new tools for automating the process
were proposed.In this work we present a formal model of
semantic reconciliation and analyze in a systematic manner
the properties of the process outcome, primarily the inherent
uncertainty of the matching process and how it reflects on
the resulting mappings.An important feature of this research
is the identification and analysis of factors that impact the

In a multidatabase system, schematic conflicts between
two objects are usually of interest only when the
objects have some semantic similarity. We use the concept
of semantic proximity, which is essentially an abstraction/
mapping between the domains of the two objects associated
with the context of comparison. An explicit though
partial context representation is proposed and the specificity
relationship between contexts is defined. The contexts are
organized as a meet semi-lattice and associated operations
like the greatest lower bound are defined. The context of

EXPRESS is an experimental prototype data translation system which can access a wide
variety of data and restructure it for new uses. The system is driven by two very high level
nonprocedural languages: DEFINE for data description and CONVERT for data restructuring.
Program generation and cooperating process techniques are used to achieve efficient operation.
This paper describes the design and implementation of EXPRESS. DEFINE and CONVERT
are summarized and the implementation architecture presented.
The DEFINE description is compiled into a customized PL/l program for accessing source

Schema evolution is a problem that is faced by long-lived data. When a schema changes, existing persistent data can become inaccessible unless the database system provides mechanisms to access data created with previous versions of the schema. Most existing systems that support schema evolution focus on changes local to individual types within the schema, thereby limiting the changes that the database maintainer can perform. We have developed a model of type changes involving multiple types.

A database view is a portion of the data structured in a way suitable to a specific
on views must be translated into updates on the underlying database. This
translation process in the relational model.
The procedure is as follows: first, a “complete” set of updates is defined such
(i) together with every update the set contains a “return” update, that is, one
back to the original state;
(ii) given two updates in the set, their composition is also in the set.
To translate a complete set, we define a mapping called a “translator,” that

A sound and complete axiomatic model is proposed for dynamic schema evolution (DSE) in objectbase systems (OBSs) that supports the fundamental concepts of object-oriented computing such as subtyping and property inheritance. The model can infer all schema relationships from two identified input sets associated with each type called the essential supertypes and essential properties. These sets are typically specified by schema designers but can be automatically supplied within an OBS. The inference mechanism performed by the model has a proven termination.

Schema matching is a basic problem in many
database application domains, such as data integration, Ebusiness,
data warehousing, and semantic query processing.
In current implementations, schema matching is typically performed
manually, which has significant limitations. On the
other hand, previous research papers have proposed many
techniques to achieve a partial automation of the match operation
for specific application domains. We present a taxonomy
that covers many of these existing approaches, and we
describe the approaches in some detail. In particular,we distinguish