Informix parallel data query (PDQ)

The PDQ project, which enables the Informix relational DBMS to perform parallel query evaluation on shared memory multiprocessors, is discussed. It is built on the Informix multithreaded server, which provides efficient creation and synchronization of parallel threads. The operators that are parallelized include scan, sort, join, and aggregate. Parallelization is achieved through the use of horizontal table partitioning and the exchange operator, which was developed as part of the Volcano research DBMS. The exchange operator initiates parallel threads, manages data flow between threads, and provides for partitioning of data among threads.<
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