Master Redis 5: Using ZPOPMAX, ZPOPMIN, BZPOPMAX and BZPOPMIN

Redis 5 has been released, adding four new sorted‑set commands:

ZPOPMAX

ZPOPMIN

BZPOPMAX

BZPOPMIN

Below are the purpose and usage of each command.

ZPOPMAX

Command: ZPOPMAX key [count] Effect:

Removes and returns the count elements with the highest scores from the specified sorted set. If count is omitted, the default is 1. When count > 1, the returned elements are ordered by score, highest first.

Example:

# Add elements
redis> ZADD myzset 1 "one"
(integer) 1
redis> ZADD myzset 2 "two"
(integer) 1
redis> ZADD myzset 3 "three"
(integer) 1
# View set with scores
redis> ZRANGE myzset 0 -1 WITHSCORES
1) "one"
2) "two"
3) "three"
# Pop two highest‑score elements
redis> ZPOPMAX myzset 2
1) "three"
2) "two"

ZPOPMIN

Command: ZPOPMIN key [count] Effect:

Same as ZPOPMAX but returns the elements with the lowest scores.

BZPOPMAX

Command: BZPOPMAX key [key ...] timeout Effect:

BZPOPMAX is the blocking version of ZPOPMAX; it behaves like ZPOPMAX but blocks when the target set is empty, waiting up to timeout seconds (0 means block indefinitely).

Example:

In window 1:

# Add elements to a set
redis> ZADD myzset2 1 "one" 2 "two"
(integer) 2
# View set with scores
redis> ZRANGE myzset2 0 -1 WITHSCORES
1) "one"
2) "two"
# Pop the highest‑score element, leaving one element
redis> BZPOPMAX myzset2 0
1) "two"

In window 2, add another element:

redis> ZADD myzset2 3 "tree"
(integer) 1

View window 1:

redis> BZPOPMAX myzset2 0
1) "tree"

BZPOPMIN

Command: BZPOPMIN key [key ...] timeout Effect:

Same as BZPOPMAX but returns the element with the lowest score.