There are different levels at which parallelism can be introduced to the database system but in general there are two types of parallel optimization tasks for databases. First, that is a speedup in query execution time. The second task is such a scaleup of the system that it was able to execute more tasks in the time unit. This situation is the subject of interest of the following paper. Authors introduce the parallelization method based on the speculative execution for the database systems which are expected to give answers to complex queries coming from different sources as soon as possible. Assume that W queries wait for execution and that the best execution plan developed by the DBMS for the first query does not use full available computing power. Thus, in parallel to the first query, some excessive computations can be executed, which in further steps would reduce the execution time of the consecutive queries increasing throughput of the system. The paper introduces the idea of speculative computations, presents possible risks and benefits of using this method and also an analyses of possible execution time reduction for different models of speculative parallelization .
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