Redis HyperLogLog Pfmerge 命令

redis 127.0.0.1:6379> PFMERGE KEY1 KEY@... KEYN

redis 127.0.0.1:6379> PFADD hll1 foo bar zap a 
(integer) 1 
redis 127.0.0.1:6379> PFADD hll2 a b c foo 
(integer) 1 
redis 127.0.0.1:6379> PFMERGE hll3 hll1 hll2 
OK 
redis 127.0.0.1:6379> PFCOUNT hll3 
(integer) 6