Comment utiliser les listes triées Redis

Un ensemble trié associe un rang à chaque élément d'un ensemble.

Les ensembles triés fonctionnent de la même manière que les ensembles et utilisent des commandes similaires, saufSest maintenantZ, par exemple:

  • SADD->ZADD
  • SPOP->ZPOP

Mais ils sont légèrement différents.

ZADDaccepte unBut:

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: