BZMPOP

Introduction

In Dragonfly, as well as in Redis and Valkey, the BZMPOP command pops one or more members (element-score pairs) from the first non-empty sorted set in the provided list of key names. It will block the connection for a specified period until a member is available to pop.

Syntax

BZMPOP timeout numkeys key [key ...] <MIN | MAX> [COUNT count]

• Time complexity: O(K) + O(M*log(N)) where K is the number of provided keys, N being the number of elements in the sorted set, and M being the number of elements popped.
• ACL categories: @write, @sortedset, @slow, @blocking

BZMPOP is the blocking variant of the ZMPOP command.

When any of the sorted sets contains elements, this command behaves exactly like ZMPOP. When used inside a MULTI/EXEC block, this command also behaves exactly like ZMPOP. When all sorted sets are empty, Dragonfly will block the connection until another client adds members to one of the keys or until the timeout (a double value specifying the maximum number of seconds to block) elapses. A timeout of zero can be used to block indefinitely.

Return Values

• Null reply: when no member could be popped and the timeout is reached.
• Array reply: a two-element array with the first element being the name of the key from which members were popped, and the second element is an array of the popped members. Every entry in the elements array is also an array that contains the member and its score.