Menno Tammens

  • Citations Per Year
Learn More
In this paper, we want to draw the attention of the database community to the problem of online schema changes: changing the schema of a database without blocking concurrent transactions. We have identified important classes of relational schema transformations that we want to perform online, and we have identified general requirements for the mechanisms(More)
This paper presents a benchmark for measuring the blocking behavior of schema transformations in relational database systems. As a basis for our benchmark, we have developed criteria for the functionality and performance of schema transformation mechanisms based on the characteristics of state of the art approaches. To address limitations of existing(More)
In earlier work we have extended the TPC-C benchmark with basic and complex schema transformations. This paper uses this benchmark to investigate the blocking behaviour of online schema transformations in PostgreSQL, MySQL and Oracle 11g. First we discuss experiments using the data definition language of the DBMSs, which show that all complex operations are(More)
In a P2P system, a peer may select one or more other peers to upload or download a specific file or content. Typically such peers are selected in a random fashion. Such peers can be located anywhere. This might lead to large amounts of traffic across the planet. To improve this situation, solutions are developed to chose peers based on their network(More)
  • 1