The GETSET command sets a key to a new value, returning the old value as the There are a number of commands for operating on strings. The final value will always beġ2 and the read-increment-set operation is performed while all the otherĬlients are not executing a command at the same time. Increment to 11, and set the new value to 11. Happen that client 1 reads "10", client 2 reads "10" at the same time, both The same key will never enter into a race condition. That even multiple clients issuing INCR against There are other similar commands like INCRBY,Īlways the same command, acting in a slightly different way. Increments it by one, and finally sets the obtained value as the new value. The INCR command parses the string value as an integer, For instance, one is atomic increment: > set counter 100 Or the opposite, that it only succeed if the key already exists: > set mykey newval nxĮven if strings are the basic values of Redis, there are interesting operations For example, I may ask SET to fail if the key already exists, The SET command has interesting options, that are provided as additionalĪrguments. Values can be strings (including binary data) of every kind, for instance youĬan store a jpeg image inside a value. The key is associated with a non-string value. Note that SET will replace any existing valueĪlready stored into the key, in the case that the key already exists, even if > set mykey somevalueĪs you can see using the SET and the GET commands are the way we setĪnd retrieve a string value. Will be performed via redis-cli in this tutorial). Let's play a bit with the string type, using redis-cli (all the examples The string data type is usefulįor a number of use cases, like caching HTML fragments or pages. We are mapping a string to another string. Since Redis keys are strings, when we use the string type as a value too, It is the only data type in Memcached, so it is also very natural The Redis String type is the simplest type of value you can associate withĪ Redis key. The maximum allowed key size is 512 MB.Dots or dashes are often used for multi-wordįields, as in "comment:4321:reply.to" or "comment:4321:reply-to". While short keys will obviouslyĬonsume a bit less memory, your job is to find the right balance. The key object itself and the value object. Is more readable and the added space is minor compared to the space used by "u1000flw" as a key if you can instead write "user:1000:followers". Very short keys are often not a good idea.With SHA1) is a better idea, especially from the perspective of memory
Is to match the existence of a large value, hashing it (for example Idea not only memory-wise, but also because the lookup of the key in theĭataset may require several costly key-comparisons. For instance a key of 1024 bytes is a bad
Key, from a string like "foo" to the content of a JPEG file. Redis keys are binary safe, this means that you can use any binary sequence as a For a general overview of the data types, see the data types introduction. The following is a hands-on tutorial that teaches the core Redis data types using the Redis CLI.
STACK ON SAFE KEY HOW TO
Learning the basic Redis data types and how to use them
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