Redis Sorted Sets: ZADD

Last update on July 24 2024 13:20:48 (UTC/GMT +8 hours)

Redis ZADD Command

Redis ZADD command is used to add all the specified members with the specified scores to the sorted set stored at key. If a specified member is an existing member of the stored set, the score is updated and the element reinserted at the right position to ensure the correct ordering. A new sorted set with the specified members as sole members is created, when key dies not exists or the sorted set was empty. If the key exists but does not hold a sorted set, an error is returned.

Here are some common uses and scenarios for the "ZADD" command:

Leaderboards: Manage leaderboards by adding players and their scores to a sorted set.
Ranking Systems: Implement ranking systems where members are scored and ranked based on their scores.
Priority Queues: Create priority queues where members are sorted based on their scores.
Data Sorting: Sort data by numeric or lexical scores for efficient retrieval.
Range Queries: Perform range queries to fetch members within a specified score range efficiently.

Syntax:

ZADD KEY_NAME SCORE1 VALUE1.. SCOREN VALUEN

Available since

1.2.0.

Return Value

Integer replies The number of elements added to the sorted sets, not including elements already existing for which the score was updated.

Return Value Type

Integer

Example: Redis ZADD

127.0.0.1:6379> ZADD mycolorset 1 white
(integer) 1
127.0.0.1:6379> ZADD mycolorset 2 black
(integer) 1
127.0.0.1:6379> ZADD mycolorset 3 red
(integer) 1
127.0.0.1:6379> ZRANGE mycolorset 0 -1
1) "white"
2) "black"
3) "red"
127.0.0.1:6379> ZRANGE mycolorset 0 -1 WITHSCORES
1) "white"
2) "1"
3) "black"
4) "2"
5) "red"
6) "3"

Example: Redis ZADD : The score member can have multiple input

127.0.0.1:6379> ZADD mycolorset 4 blue 5 green
(integer) 2
127.0.0.1:6379> ZRANGE mycolorset 0 -1 WITHSCORES
 1) "white"
 2) "1"
 3) "black"
 4) "2"
 5) "red"
 6) "3"
 7) "blue"
 8) "4"
 9) "green"
10) "5"

Example: Redis ZADD : score is equal to the member being sort

127.0.0.1:6379> ZADD mycolorset 1 white 1 black 1 red 1 blue 1 green
(integer) 5
127.0.0.1:6379> ZRANGE mycolorset 0 -1 WITHSCORES
 1) "black"
 2) "1"
 3) "blue"
 4) "1"
 5) "green"
 6) "1"
 7) "red"
 8) "1"
 9) "white"
10) "1"

Example: Redis ZADD : duplicate member is not permitted

127.0.0.1:6379> ZADD mycolorset 1 orange
(integer) 1
127.0.0.1:6379> ZRANGE mycolorset 0 -1 WITHSCORES
 1) "black"
 2) "1"
 3) "blue"
 4) "1"
 5) "green"
 6) "1"
 7) "orange"
 8) "1"
 9) "red"
10) "1"
11) "white"
12) "1"

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