Number of items in Redis set

Question

What's the easiest way to getting the number (count) of items in Redis set? Preferably without the need to dump whole set and count the lines... So far, I have found only BITCOUNT, which I have not found that useful...

Answer 1

The SCARD command returns the cardinality (i.e. number of items) of a Redis set.

http://redis.io/commands/scard

There is a similar command (ZCARD) for sorted sets.

Answer 2

Also if you have a sorted set, you can use the ZCOUNT command to get the number of elements in the sorted set at key with a score between min and max.

Example:

ZCOUNT myzset 2 15

return count of elements with score >= 2 and <= 15

Answer 3

for python you can use scard.

lebgth=db.scard(key)