PFMERGE destkey sourcekey [sourcekey …]

Time complexity: O(N) to merge N HyperLogLogs, but with high constant times.

Merge multiple HyperLogLog values into an unique value that will approximate the cardinality of the union of the observed Sets of the source HyperLogLog structures.

If the destination variable exists, it is treated as one of the source sets and its cardinality will be included in the cardinality of the computed HyperLogLog.

: The command just returns .

*Examples

redis> PFADD hll2 a b c foo

redis> PFMERGE hll3 hll1 hll2