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System, method, and computer-readable medium for optimizing processing of distinct and aggregation queries on skewed data in a database system
System, method, and computer-readable medium for optimizing processing of distinct and aggregation queries on skewed data in a database system
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机译:用于优化对数据库系统中偏斜数据的不同查询和聚合查询的处理的系统,方法和计算机可读介质
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摘要
A system, method, and computer-readable medium for optimization of query processing in a parallel processing system are provided. Skewed values and non-skewed values are treated differently to improve upon conventional DISTINCT and aggregation query processing. Skewed attribute values on which a DISTINCT selection or group by aggregation is applied are allocated entries in a hash table. In this manner, a processing module may consult the hash table to determine if a skewed attribute value has been encountered during the query processing in a manner that precludes repetitive redistribution of rows with highly skewed attribute values on which a DISTINCT selection or group by aggregation is applied.
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