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Many analytics databases implement something even stronger than that. They keep what are called "zone maps", which are pre-computed statistics for groups of ro
by ryanworl 8y ago
Many analytics databases implement something even stronger than that.
They keep what are called "zone maps", which are pre-computed statistics for groups of rows that contain those same aggregate functions. This allows for those types of analytics functions, but also for pruning of data to read at all during regular table scans further in the query execution.