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ZREMRANGEBYRANK

Introduction and Use Case(s)​

ZREMRANGEBYRANK removes all elements in a sorted set within the given rank range. This command is useful for trimming sets, removing outdated data, or maintaining a fixed number of records.

Syntax​

ZREMRANGEBYRANK key start stop

Parameter Explanations​

  • key: The name of the sorted set.
  • start: The starting rank (inclusive) to remove. Ranks are 0-based indices where 0 is the element with the smallest score.
  • stop: The ending rank (inclusive) to remove.

Return Values​

The command returns an integer indicating the number of members removed.

Examples:​

  • If three members are removed, it returns (integer) 3.
  • If no members are found within the specified rank range, it returns (integer) 0.

Code Examples​

dragonfly$> ZADD myset 1 "one" 2 "two" 3 "three"
(integer) 3
dragonfly$> ZREMRANGEBYRANK myset 0 1
(integer) 2
dragonfly$> ZRANGE myset 0 -1 WITHSCORES
1) "three"
2) "3"

Best Practices​

  • Use ZRANGEBYRANK before ZREMRANGEBYRANK to preview the elements that will be removed.
  • Combine ZREMRANGEBYRANK with other sorted set commands to manage your dataset efficiently.

Common Mistakes​

  • Using incorrect rank values: Ensure the start and stop parameters are within the existing ranks of the sorted set.
  • Misunderstanding ranks vs. scores: ZREMRANGEBYRANK operates on ranks, not scores.

FAQs​

Q: What happens if start and stop specify an empty range? A: No elements are removed, and the command returns 0.

Q: Can negative indices be used for start and stop? A: Yes, similar to Python slice notation, -1 refers to the last element, -2 to the second last, and so on.