Intersection of two or more sorted sets

Question

I have two sorted sets, and want to make intersection, ie. (age BETWEEN 25, 35) AND (salary BETWEEN 250, 350)

Is there a better way regarding efficiency

Answer 1

You should first check which ZSET has less elements with ZCARD, and clone and trim the shorter one.

Second, you are leaving 2 leftovers. You can reuse the same auxiliary ZSET to have a faster cleanup.

I also wanted to suggest DUMP and RESTORE for the clone, but for the sorted sets case ZUNIONSTORE is actually much faster. Here's a timing of both for a 1M elements set:

1) 1) (integer) 14
   2) (integer) 1444165498
   3) (integer) 936762
   4) Complexity info: N:1000000,M:1000000
   5) 1) "ZUNIONSTORE"
      2) "temp3"
      3) "1"
      4) "temp1"
      5) "WEIGHTS"
      6) "1"
2) 1) (integer) 13
   2) (integer) 1444165421
   3) (integer) 3166360
   4)
   5) 1) "evalsha"
      2) "48286113cfe4b389d516e98646e5f4e086decc34"
      3) "2"
      4) "temp1"
      5) "temp2"
      6) "0"