Curt J. Ellmann

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Many modern software systems provide progress indicators for long-running tasks. These progress indicators make systems more user-friendly by helping the user quickly estimate how much of the task has been completed and when the task will finish. However, none of the existing commercial RDBMSs provides a non-trival progress indicator for long-running(More)
Recently, progress indicators have been proposed for long-running SQL queries in RDBMSs. Although the proposed techniques work well for a subset of SQL queries, they are preliminary in the sense that (1) they cannot provide non-trivial estimates for some SQL queries, and (2) the provided estimates can be rather imprecise in certain cases. In this paper, we(More)
Recently, Haas and Hellerstein proposed the hash ripple join algorithm in the context of online aggregation. Although the algorithm rapidly gives a good estimate for many join-aggregate problem instances, the convergence can be slow if the number of tuples that satisfy the join predicate is small or if there are many groups in the output. Furthermore, if(More)
This paper presents a number of new techniques for parallelizing geo-spatial database systems and discusses their implementation in the Paradise object-relational database system. The effectiveness of these techniques is demonstrated using a variety of complex geo-spatial queries over a 120 GB global geo-spatial data set.
In a typical data warehouse, materialized views are used to speed up query execution. Upon updates to the base relations in the warehouse, these materialized views must also be maintained. The need to maintain these materialized views can have a negative impact on performance that is exacerbated in parallel RDBMSs, since simple single-node updates to base(More)
The maintenance of materialized aggregate join views is a well-studied problem. However, to date the published literature has largely ignored the issue of concurrency control. Clearly, immediate materialized view maintenance with transactional consistency, if enforced by generic concurrency control mechanisms, can result in low levels of concurrency and(More)
Traditional workload management methods mainly focus on the current system status while information about the interaction between queued and running transactions is largely ignored. This paper proposes using transaction reordering, a workload management method that considers both the current system status and information about the interaction between queued(More)
With the increasing popularity of operational data warehousing, the ability to load data quickly and continuously into an RDBMS is becoming more and more important. However, in the presence of materialized join views, loading data concurrently into multiple base relations of the same materialized join view can cause a severe deadlock problem. To solve this(More)