Niko Neugebauer • 10/13/2018

Approximate Distinct Count

This technical article discusses the challenges of exact COUNT(DISTINCT) operations on large datasets, such as high memory consumption and long execution times. It introduces approximate distinct count algorithms like HyperLogLog, highlighting their trade-offs in speed and accuracy. The piece focuses on Microsoft's implementation of APPROX_COUNT_DISTINCT in Azure SQL Database and SQL Server 2019, placing it in the context of similar features in other major data platforms like Amazon Redshift and BigQuery.

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#data processing #algorithm #Big Data