Redis Cheat Sheet
About Redis (the official site , materials on Habré ) has been written a lot, but to this day I didn’t have enough material to serve as a cheat sheet for its practical use, as well as a reference book on basic theoretical points. I will try to fill this gap in the rich knowledge base of Habr.
I set a goal to show the capabilities of Redis using code examples. After the publication I will accept any suggestions for improving the material.
It uses communication with the server through the console client, but based on the examples provided, you can easily find the implementation of these examples in the client libraries in your favorite language.
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Redis is a key-value data store. Key Facts:
There is a separate good article about Redis data types: “Data Structures Used in Redis” .
The console uses the
Task 1, creation, selection, modification, deletion and basic information about objects.
Set and read values with keys of the form
Details on the commands related to this task can be found in the documentation in the Keys and Strings sections.
Task 2, the lifetime of the object.
By default, the object is not limited to the lifetime, so
Details on the commands related to this task can be found in the documentation in the Keys and Strings sections.
Task 3, pipelining, executing several commands in one request.
Pipelining is useful for optimizing bulk inserts.
Task 4, transaction.
The following basic commands are used to implement transactions in Redis:
Details on the commands related to this task can be found in the documentation in the Transactions section.
Task 5, demonstrate basic string operations.
Task 6, demonstrate operations on numbers.
Details on the commands related to these tasks can be found in the documentation in the Strings section.
Task 7, create a list, demonstrate basic list operations.
Details on the commands related to this task can be found in the documentation in the Lists section.
Task 8, create a set, demonstrate the basic operations on sets.
Details on the commands related to this task can be found in the documentation in the Sets section.
Task 9, create an ordered set and demonstrate the basic operations on it.
In an ordered set, the elements are compared by the additional parameter “score”.
Details on the commands related to this task can be found in the documentation in the Sorted sets section.
Task 10, Create a hash table and demonstrate basic hash operations.
Details on the commands related to this task can be found in the documentation in the Hashes section.
Task 11, subscribe to messages on one client and send a message from another.
We present the windows of two clients; in the first window, a subscription to messages is made and the message sent from the second window is visible.
Task 12, subscribe to messages on one client and send a message from another. Subscription exercise using templates.
We present the windows of two clients; in the first window, a subscription to messages is made and the message sent from the second window is visible.
Details on the commands related to these tasks can be found in the documentation in the Pub / Sub section.
I set a goal to show the capabilities of Redis using code examples. After the publication I will accept any suggestions for improving the material.
It uses communication with the server through the console client, but based on the examples provided, you can easily find the implementation of these examples in the client libraries in your favorite language.
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Keys
Redis is a key-value data store. Key Facts:
- The keys in Redis are binary safe ( binary safe ) strings.
- Keys that are too long are a bad idea, not only because of the memory they occupy, but also because of the increase in the search time for a particular key in the set due to the costly comparison.
- A good idea is to stick to the schema when building keys: “object-type: id: field”.
Redis data types
- Strings (strings). Redis base data type. The strings in Redis are binary-safe, they can be used in the same way as numbers, limited to 512 MB in size.
- Lists (lists). Classic lists of strings, ordered in order of insertion, which is possible from the side of the head, and from the side of the tail of the list. The maximum number of elements is 2 32 - 1.
- Sets . Sets of lines in the mathematical sense: not ordered, support insert operations, check element occurrences, intersections and set differences. The maximum number of elements is 2 32 - 1.
- Hash tables . Classic hash tables or associative arrays. The maximum number of key-value pairs is 2 32 - 1.
- Ordered sets (sorted sets). An ordered set differs from the usual one in that its elements are ordered by the special parameter “score”.
There is a separate good article about Redis data types: “Data Structures Used in Redis” .
Basic operations
The console uses the
redis-cli client program to communicate with Redis. Consider the basic operations.Task 1, creation, selection, modification, deletion and basic information about objects.
Set and read values with keys of the form
test:1:* . Find out the type of value, check the existence of the element, extract all fields of the test:1 entry, delete the field of the test:1 entry. redis 127.0.0.1:6379> set test:1:string "my binary safe string" OK redis 127.0.0.1:6379> get test:1:string "my binary safe string" redis 127.0.0.1:6379> getset test:1:string "other value" "my binary safe string" redis 127.0.0.1:6379> type test:1:string string redis 127.0.0.1:6379> set test:1:vlaue "487" OK redis 127.0.0.1:6379> rename test:1:vlaue test:1:value OK redis 127.0.0.1:6379> exists test:1:vlaue (integer) 0 redis 127.0.0.1:6379> exists test:1:value (integer) 1 redis 127.0.0.1:6379> keys test:1:* 1) "test:1:string" 2) "test:1:value" redis 127.0.0.1:6379> del test:1:value (integer) 1 redis 127.0.0.1:6379> keys test:1:* 1) "test:1:string" Details on the commands related to this task can be found in the documentation in the Keys and Strings sections.
Task 2, the lifetime of the object.
redis 127.0.0.1:6379> ttl test:1:string (integer) -1 redis 127.0.0.1:6379> expire test:1:string 6000 (integer) 1 redis 127.0.0.1:6379> ttl test:1:string (integer) 5997 By default, the object is not limited to the lifetime, so
TTL returns -1, after setting the value with the EXPIRE command, the TTL command already returns the remaining number of seconds.Details on the commands related to this task can be found in the documentation in the Keys and Strings sections.
Task 3, pipelining, executing several commands in one request.
PS D:\Programs\Redis\64bit> "set test:1:pvalue 'test'`r`nget test:1:pvalue" | .\redis-cli OK "test" Pipelining is useful for optimizing bulk inserts.
Task 4, transaction.
The following basic commands are used to implement transactions in Redis:
MULTI- start recording commands for the transaction.EXEC- execute the recorded commands.DISCARD- delete all recorded commands.WATCHis a command that provides “check-and-set” (CAS) behavior — a transaction is executed only if other clients have not changed the value of the variable. Otherwise,EXECwill not execute the recorded commands.
redis 127.0.0.1:6379> multi OK redis 127.0.0.1:6379> set test:1:trValue "1" QUEUED redis 127.0.0.1:6379> incr test:1:trValue QUEUED redis 127.0.0.1:6379> decr test:1:trValue QUEUED redis 127.0.0.1:6379> exec 1) OK 2) (integer) 2 3) (integer) 1 Details on the commands related to this task can be found in the documentation in the Transactions section.
Lines / numbers
Task 5, demonstrate basic string operations.
redis 127.0.0.1:6379> set test:1:string "hello" OK redis 127.0.0.1:6379> append test:1:string " world!" (integer) 12 redis 127.0.0.1:6379> get test:1:string "hello world!" redis 127.0.0.1:6379> strlen test:1:string (integer) 12 redis 127.0.0.1:6379> getrange test:1:string 6 10 "world" redis 127.0.0.1:6379> setrange test:1:string 6 "habrahabr!" (integer) 16 redis 127.0.0.1:6379> get test:1:string "hello habrahabr!" Task 6, demonstrate operations on numbers.
redis 127.0.0.1:6379> set test:1:int 1 OK redis 127.0.0.1:6379> incr test:1:int (integer) 2 redis 127.0.0.1:6379> decr test:1:int (integer) 1 redis 127.0.0.1:6379> incrby test:1:int 20 (integer) 21 redis 127.0.0.1:6379> decrby test:1:int 15 (integer) 6 Details on the commands related to these tasks can be found in the documentation in the Strings section.
Lists
Task 7, create a list, demonstrate basic list operations.
redis 127.0.0.1:6379> rpush test:1:messages "Hello, world!" (integer) 1 redis 127.0.0.1:6379> rpush test:1:messages "Hello, user!" (integer) 2 redis 127.0.0.1:6379> rpush test:1:messages "Wow!" (integer) 3 redis 127.0.0.1:6379> lrange test:1:messages 0 2 1) "Hello, world!" 2) "Hello, user!" 3) "Wow!" redis 127.0.0.1:6379> llen test:1:messages (integer) 3 redis 127.0.0.1:6379> lpop test:1:messages "Hello, world!" redis 127.0.0.1:6379> lpop test:1:messages "Hello, user!" redis 127.0.0.1:6379> lpop test:1:messages "Wow!" redis 127.0.0.1:6379> llen test:1:messages (integer) 0 Details on the commands related to this task can be found in the documentation in the Lists section.
Sets, ordered sets
Task 8, create a set, demonstrate the basic operations on sets.
redis 127.0.0.1:6379> sadd test:1:fruits "banana" (integer) 1 redis 127.0.0.1:6379> sadd test:1:fruits "apple" (integer) 1 redis 127.0.0.1:6379> sadd test:1:fruits "strawberry" (integer) 1 redis 127.0.0.1:6379> sadd test:1:yellowThings "banana" (integer) 1 redis 127.0.0.1:6379> sadd test:1:yellowThings "apple" (integer) 1 redis 127.0.0.1:6379> sadd test:1:redThings "strawberry" (integer) 1 redis 127.0.0.1:6379> scard test:1:fruits (integer) 3 redis 127.0.0.1:6379> sdiff test:1:fruits test:1:yellowThings 1) "strawberry" redis 127.0.0.1:6379> sdiffstore test:1:noYellowFruits test:1:fruits test:1:yellowThings (integer) 1 redis 127.0.0.1:6379> sinter test:1:yellowThings test:1:fruits 1) "banana" 2) "apple" redis 127.0.0.1:6379> sismember test:1:fruits "banana" (integer) 1 redis 127.0.0.1:6379> sismember test:1:fruits "tomato" (integer) 0 redis 127.0.0.1:6379> smembers test:1:noYellowFruits 1) "strawberry" redis 127.0.0.1:6379> smove test:1:yellowThings test:1:redThings "apple" (integer) 1 redis 127.0.0.1:6379> smembers test:1:redThings 1) "strawberry" 2) "apple" redis 127.0.0.1:6379> spop test:1:redThings "apple" redis 127.0.0.1:6379> srandmember test:1:fruits "apple" redis 127.0.0.1:6379> srem test:1:fruits "banana" (integer) 1 redis 127.0.0.1:6379> sunion test:1:yellowThings test:1:redThings 1) "strawberry" 2) "banana" redis 127.0.0.1:6379> sunionstore test:1:allThings test:1:yellowThings test:1:redThings (integer) 2 redis 127.0.0.1:6379> smembers test:1:allThings 1) "strawberry" 2) "banana" Details on the commands related to this task can be found in the documentation in the Sets section.
Task 9, create an ordered set and demonstrate the basic operations on it.
In an ordered set, the elements are compared by the additional parameter “score”.
redis 127.0.0.1:6379> zadd hackers 1953 "Richard Stallman" (integer) 1 redis 127.0.0.1:6379> zadd hackers 1940 "Alan Kay" (integer) 1 redis 127.0.0.1:6379> zadd hackers 1965 "Yukihiro Matsumoto" (integer) 1 redis 127.0.0.1:6379> zadd hackers 1916 "Claude Shannon" (integer) 1 redis 127.0.0.1:6379> zadd hackers 1969 "Linus Torvalds" (integer) 1 redis 127.0.0.1:6379> zadd hackers 1912 "Alan Turing" (integer) 1 redis 127.0.0.1:6379> zrange hackers 0 -1 1) "Alan Turing" 2) "Claude Shannon" 3) "Alan Kay" 4) "Richard Stallman" 5) "Yukihiro Matsumoto" 6) "Linus Torvalds" redis 127.0.0.1:6379> zrevrange hackers 0 -1 1) "Linus Torvalds" 2) "Yukihiro Matsumoto" 3) "Richard Stallman" 4) "Alan Kay" 5) "Claude Shannon" 6) "Alan Turing" redis 127.0.0.1:6379> zrangebyscore hackers -inf 1950 1) "Alan Turing" 2) "Claude Shannon" 3) "Alan Kay" redis 127.0.0.1:6379> zremrangebyscore hackers 1940 1960 (integer) 2 redis 127.0.0.1:6379> zrange hackers 0 -1 1) "Alan Turing" 2) "Claude Shannon" 3) "Yukihiro Matsumoto" 4) "Linus Torvalds" Details on the commands related to this task can be found in the documentation in the Sorted sets section.
Hash tables
Task 10, Create a hash table and demonstrate basic hash operations.
redis 127.0.0.1:6379> hset users:1 name "Andrew" (integer) 1 redis 127.0.0.1:6379> hset users:1 email "andrew@example.com" (integer) 1 redis 127.0.0.1:6379> hkeys users:1 1) "name" 2) "email" redis 127.0.0.1:6379> hvals users:1 1) "Andrew" 2) "andrew@example.com" redis 127.0.0.1:6379> hgetall users:1 1) "name" 2) "Andrew" 3) "email" 4) "andrew@example.com" redis 127.0.0.1:6379> hset users:1 test 1 (integer) 1 redis 127.0.0.1:6379> hincrby users:1 test 123 (integer) 124 redis 127.0.0.1:6379> hvals users:1 1) "Andrew" 2) "andrew@example.com" 3) "124" redis 127.0.0.1:6379> hdel users:1 test (integer) 1 redis 127.0.0.1:6379> hvals users:1 1) "Andrew" 2) "andrew@example.com" Details on the commands related to this task can be found in the documentation in the Hashes section.
Pub / Sub, Redis posts
Task 11, subscribe to messages on one client and send a message from another.
We present the windows of two clients; in the first window, a subscription to messages is made and the message sent from the second window is visible.
redis 127.0.0.1:6379> SUBSCRIBE messages Reading messages... (press Ctrl-C to quit) 1) "subscribe" 2) "messages" 3) (integer) 1 1) "message" 2) "messages" 3) "Hello world!" redis 127.0.0.1:6379> PUBLISH messages "Hello world!" (integer) 1 Task 12, subscribe to messages on one client and send a message from another. Subscription exercise using templates.
We present the windows of two clients; in the first window, a subscription to messages is made and the message sent from the second window is visible.
redis 127.0.0.1:6379> PSUBSCRIBE news.* Reading messages... (press Ctrl-C to quit) 1) "psubscribe" 2) "news.*" 3) (integer) 1 1) "pmessage" 2) "news.*" 3) "news.art" 4) "New picture!" 1) "pmessage" 2) "news.*" 3) "news.cinema" 4) "New movie!" redis 127.0.0.1:6379> PUBLISH news.art "New picture!" (integer) 1 redis 127.0.0.1:6379> PUBLISH news.cinema "New movie!" (integer) 1 Details on the commands related to these tasks can be found in the documentation in the Pub / Sub section.
Source: https://habr.com/ru/post/204354/
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