Shulou(Shulou.com)06/01 Report--

# Overview of collections

Similar to the set in mathematics, the operation of the set includes adding and deleting elements, intersection and difference of multiple sets and so on.

The key in the operation is understood as the name of the collection. For example, in the Weibo application, you can put all the followers of a user in a collection and all its fans in a collection. Because redis is very humanized for the collection to provide intersection, union, difference product and other operations, so long can be very convenient to achieve such as concern, common preferences, second friends and other functions, for all the above collection operations, you can also use different commands to choose to return the results to the client or save the set to a new collection.

Qq has a social function called "friend tag". You can tag your friends, such as "Beauty", "Tuhao", "Brother" and so on. You can use the collection of redis to store each customer's tag in a collection.

# Common commands

# insert elements

127.0.0.1 6379 > sadd set1 dang # put elements into set1

(integer) 1

127.0.0.1 purl 6379 > sadd set1 linux

(integer) 1

127.0.0.1 purl 6379 > sadd set1 python

(integer) 1

127.0.0.1 purl 6379 > sadd set1 nosql

(integer) 1

# Delete elements

Srem set1 aaaa / / Delete elements

Spop set1 / / randomly take out an element and delete it

# get elements

127.0.0.1 smembers set1 6379 > get all the elements in the collection

1) "linux"

2) "nosql"

3) "python"

4) "dang"

Sismember seta aaa / / determines whether an element belongs to a collection

Srandmember seta / / randomly take out an element but do not delete it

# intersection and merge difference

Sdiff seta setb / / difference set, taking seta as the standard

Sdiffstore seta setb setc / / the difference set is stored and stored in seta.

Sinter seta setb / / find the intersection

Sinterstore seta setb setc / / intersect and store, store to seta

Sunion seta setb / / Union set

Sunionstore sete seta setb / / join and store the result in sete

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