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PFMERGE

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PFMERGE destkey [sourcekey [sourcekey ...]]
Group
HyperLogLog
Complexity
O(N) for N source keys
Arity
-2 (at least 2 words, counting the command name)
Flags
write
Keys
first 1, last final argument, step 1
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PFMERGE combines the source HyperLogLogs into destkey, so that its estimate covers every element seen by any of them. If destkey already holds a HyperLogLog, it is part of the union too; otherwise it is created. Missing sources are skipped. With no sources, PFMERGE just makes sure destkey exists as a HyperLogLog. The destination keeps its time to live.

In a cluster, all keys must hash to the same slot.

Return value

Section titled “Return value”
Case RESP2 RESP3
Always Simple string OK Simple string OK

The errors are those of PFADD, for the destination or any source.

Examples

Section titled “Examples”
127.0.0.1:6379> PFADD day:1 alice bob carol
(integer) 1
127.0.0.1:6379> PFADD day:2 carol dave
(integer) 1
127.0.0.1:6379> PFMERGE week day:1 day:2
OK
127.0.0.1:6379> PFCOUNT week
(integer) 4

Compatibility

Section titled “Compatibility”

Same as Redis 7 and Valkey 8.

See also

Section titled “See also”

PFADD, PFCOUNT