Code
redis
# Add and remove members
SADD tags:post:1 "mongo" "db" "nosql"
SADD tags:post:2 "postgres" "db" "sql"
SREM tags:post:1 "nosql"
# Membership and size
SISMEMBER tags:post:1 "db"
SCARD tags:post:1
SMEMBERS tags:post:1
# Set operations
SINTER tags:post:1 tags:post:2 # common tags
SUNION tags:post:1 tags:post:2 # all tags
SDIFF tags:post:1 tags:post:2 # in 1 but not 2
# Random member and pop
SRANDMEMBER tags:post:1
SPOP tags:post:1