George Papastefanatos

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Databases are continuously evolving environments, where design constructs are added, removed or updated rather often. Small changes in the database configurations might impact a large number of applications and data stores around the system: queries and data entry forms can be invalidated, application programs might crash. HECATAEUS is a tool, which(More)
In this paper, we discuss the problem of performing impact prediction for changes that occur in the schema/structure of the data warehouse sources. We abstract Extract-Transform-Load (ETL) activities as queries and sequences of views. ETL activities and its sources are uniformly modeled as a graph that is annotated with policies for the management of(More)
In this paper, we deal with the problem of performing what-if analysis for changes that occur in the schema/structure of the data warehouse sources. We abstract software modules, queries, reports and views as (sequences of) queries in SQL enriched with functions. Queries and relations are uniformly modeled as a graph that is annotated with policies for the(More)
— HECATAEUS is an open-source software tool for enabling impact prediction, what-if analysis, and regulation of relational database schema evolution. We follow a graph theo-retic approach and represent database schemas and database constructs, like queries and views, as graphs. Our tool enables the user to create hypothetical evolution events and examine(More)
Databases are continuously evolving environments, where design constructs are added, removed or updated rather often. Research has extensively dealt with the problem of database evolution. Nevertheless, problems arise with existing queries and applications, mainly due to the fact that, in most cases, their role as integral parts of the environment is not(More)
Traditional modeling techniques typically focus on the static part of databases and ignore their dynamic part (e.g., queries or data-centric workflows). In this paper, we first introduce and sketch a graph-based model that captures relations, views, constraints and queries. We then present HECATAEUS, a tool for implementing and visualizing the above(More)
The administrators and designers of modern Information Systems face the problem of maintaining their systems in the presence of frequently occurring changes in any counterpart of it. In other words, when a change occurs in any point of the system –e.g., source, schema, view, software construct– they should propagate the change in all the involved parts of(More)
The web of data has brought forth the need to preserve evolving information within linked datasets; however, a basic requirement of data preservation is the maintenance of the datasets' structural aspects as well. In this paper , we present a linked data approach for the preservation and archiving of open heterogeneous datasets that evolve through time, at(More)
The purpose of data visualization is to offer intuitive ways for information perception and manipulation, especially for non-expert users. The Web of Data has realized the availability of a huge amount of datasets. However, the volume and heterogeneity of available information make it difficult for humans to manually explore and analyse large datasets. In(More)