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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 re-lational 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)
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