Redis HyperLogLog: PFCOUNT

PFCOUNT key [key ...]

Redis PFCOUNT command is used to get the approximated cardinality computed by the HyperLogLog data structure stored in the specified variable. If the key does not exist, then it returns 0.

Syntax:

PFCOUNT KEY1 KEY@... KEYN

Available since

2.8.9.

Return Value

Integer reply approximated a number of unique elements.

When PFCOUNT command is used with multiple keys, then it returns approximated cardinality of the union of the HyperLogLogs.

Return Value Type

Integer

Example: Redis PFCOUNT

redis 127.0.0.1:6379> PFADD mykey a b c d e f g h i j
(integer) 1
redis 127.0.0.1:6379> PFCOUNT mykey
(integer) 10
redis 127.0.0.1:6379> PFCOUNT mykey
(integer) 10
redis 127.0.0.1:6379> PFCOUNT mykey mynewkey
(integer) 10

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