Krzysztof Stencel

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We propose a method for automatic detection of occurrences of design patterns. We also describe its proof-of-concept implementation and the results of comparative experiments with other tools. The method presented here is able to detect many nonstandard implementation variants of design patterns, while its efficiency is comparable to other state-of-the-art(More)
The relational model is the basis for most modern databases, while SQL is the most commonly used query language. However, there are data structures and computational problems that cannot be expressed using SQL-92 queries. Among them are those concerned with the bill-of-material and corporate hierarchies. A newer standard, called the SQL-99, introduced(More)
We propose a new approach to integration of distributed heterogeneous resources on the basis of a canonical object-oriented database model, a query language and updateable database views. Views are used as wrappers/mediators on top of local servers and as a data integration facility for global applications. Views support location, implementation and(More)
Recent years witnessed continuous development of database query languages and object relational mappers. One of the research fields of interest are recursive queries. The first implementations of such queries for SQL has been introduced by Oracle in 1985. However, it was the introduction of recursive Common Table Expressions into the SQL:99 standard that(More)
A recursive SQL-1999 query consists of a recursive CTE (Common Table Expression) and a query which uses it. If such a recursive query is used in a context of a selection predicate, this predicate can possibly be pushed into the CTE thus limiting the breadth and/or depth of the recursive search. This can happen e.g. after the definition of a view containing(More)
Unified State Model (USM) is a single data model that allows conveying objects of major programming languages and databases. USM exploits and emphasizes common properties of their data models. USM is equipped with mappings from these data models onto it. With USM at hand, we have faced the next natural research question whether numerous query languages for(More)
We present a new approach to the grid technology that is based on federated databases and updatable views. Views are used in two ways: (1) as wrappers of local servers that adopt local schemata to the federated database requirements; (2) as a facility for data integration and transformation into a canonical form according to the federated database schema.(More)