PFADD

The PFADD command adds elements to the HyperLogLog data structure stored at the specified key.

HyperLogLog is a probabilistic structure: it estimates the number of unique elements using a small and fixed amount of memory.

Syntax

PFADD key [element [element ...]]

Parameters

• key - HyperLogLog key name
• element - One or more elements to add

Return

Integer reply:

• 1 if at least one HyperLogLog internal register was altered.
• 0 if no HyperLogLog internal registers were altered.

Special case:

• PFADD key (no elements) creates an empty HyperLogLog if key does not exist and returns 1. If key already exists, it performs no operation and returns 0.

Examples

redis> PFADD hll1 element1
(integer) 1
redis> PFADD hll1 element2 element3 element4
(integer) 1
redis> PFADD hll1 element1 element2
(integer) 0
redis> PFADD hll1 element5
(integer) 1