Un conjunto ordenado asocia un rango a cada elemento de un conjunto.
Los conjuntos ordenados funcionan de manera similar a los conjuntos y utilizan comandos similares, exceptoSes ahoraZ, por ejemplo:
SADD->ZADDSPOP->ZPOP
Pero son ligeramente diferentes.
ZADDacepta unpuntaje:
ZADD names 1 "Flavio"
ZADD names 2 "Syd"
ZADD names 2 "Roger"As you can see, values must still be unique, but now they are associated to a score.
The score does not have to be unique.
Items in a set are always sorted by the score.
This is very useful to implement some kind of data storage tool like (usual example) a leaderboard. Or to indicate the time some item was added, with a timestamp.
You can get the score of an item using ZRANK:
ZRANK names "Flavio"List all items in a sorted set using ZRANGE, which works similarly to LRANGE in lists:
ZRANGE names 0 -1
Add WITHSCORES to also return the scores information:
You can increment the score of an item in the set using ZINCRBY.
See all the sorted sets commands here.
More redis tutorials:
- Introduction to Redis
- How to install Redis
- First steps with Redis
- Redis Lists
- Using Redis Sets
- How to use Redis Sorted Lists
- How to use Redis Hashes
- Redis Publish/subscribe