Returns the number of members of the intersect of multiple sets.
SINTERCARD
numkeys
key [key…] [LIMIT
limit]
This command is similar to SINTER
, but instead of
returning the result set, it returns just the cardinality of the result.
Returns the cardinality of the set which would result from the
intersection of all the given sets.
Keys that do not exist are considered to be empty sets. With one of the keys being an empty set, the resulting set is also empty (since set intersection with an empty set always results in an empty set).
By default, the command calculates the cardinality of the
intersection of all given sets. When provided with the optional
LIMIT
argument (which defaults to 0 and means unlimited),
if the intersection cardinality reaches limit partway through the
computation, the algorithm will exit and yield limit as the cardinality.
Such implementation ensures a significant speedup for queries where the
limit is lower than the actual intersection cardinality.
Integer reply: the number of elements in the resulting intersection.
Integer reply: the number of the elements in the resulting intersection.
O(N*M) worst case where N is the cardinality of the smallest set and M is the number of sets.
@read @set @slow
127.0.0.1:6379> SADD key1 "a"
(integer) 1
127.0.0.1:6379> SADD key1 "b"
(integer) 1
127.0.0.1:6379> SADD key1 "c"
(integer) 1
127.0.0.1:6379> SADD key1 "d"
(integer) 1
127.0.0.1:6379> SADD key2 "c"
(integer) 1
127.0.0.1:6379> SADD key2 "d"
(integer) 1
127.0.0.1:6379> SADD key2 "e"
(integer) 1
127.0.0.1:6379> SINTER key1 key2
1) "c"
2) "d"
127.0.0.1:6379> SINTERCARD 2 key1 key2
(integer) 2
127.0.0.1:6379> SINTERCARD 2 key1 key2 LIMIT 1
(integer) 1
SADD, SCARD, SDIFF, SDIFFSTORE, SINTER, SINTERSTORE, SISMEMBER, SMEMBERS, SMISMEMBER, SMOVE, SPOP, SRANDMEMBER, SREM, SSCAN, SUNION, SUNIONSTORE.