從零入手Redis緩存

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1. ##Redis介紹

Redis是一個開源的使用ANSI C語言編寫、支援網路、可基於記憶體亦可持久化的日誌型、Key-Value#資料庫，並提供多種語言的#API。從2010年3月15日起，Redis的開發工作由VMware主持。從2013年5#月開始，Redis##的開發由 Pivotal贊助。

redis

是一個key-value儲存系統。和Memcached類似，它支援儲存的value類型相對更多，包括string( 字串)、list(鍊錶)、set(集合)、zset(sorted set --##有序集合)和hash（哈希類型）。這些資料型別都支援push/pop、add/remove及取交集並集和差集及更豐富的操作，而且這些操作都是原子性的。在此基礎上，redis支援各種不同方式的排序。與memcached一樣，為了保證效率，資料都是快取在記憶體中。區別的是redis會週期性的把更新的資料寫入磁碟或把修改操作寫入追加的記錄文件，並且在此基礎上實現了master-slave(主從)同步。

Redis is a high-performance key-value database. The emergence of redis has largely compensated for memcached of this typekey/valueInsufficient storage can play a very good supplementary role to the relational database in some situations. It provides Java, C/C , C#, PHP,JavaScript,Perl,Object-C , Python, Ruby, Erlang and other clients, use very convenient. ^[1]

Redis supports master-slave synchronization. Data can be synchronized from the master server to any number of slave servers, and the slave server can be a master server associated with other slave servers. This enables Redis to perform single-level tree replication. Saving can write data intentionally or unintentionally. Since the publication/ subscription mechanism is fully implemented, when the slave database synchronizes the tree anywhere, it can subscribe to a channel and receive the complete message publishing record of the master server. Synchronization is helpful for scalability and data redundancy of read operations. The official website address of

redis is very easy to remember, it is redis.io. (I checked specifically and found that the domain name suffix io belongs to the national domain name, which is british Indian Ocean territory, that is, the British Indian Ocean Territory)

Currently, Vmware is funding the development and maintenance of the redis project.

2. Redis installation

Extract the installation file

##After decompression

Execute make to compile

Compile OK,

Enter the src directory

Redis-cli terminal operation

Redis-server file to start redis service

Redis-benchmark pressure Test file

Redis-check-xx Car inspection backup file script

Create the Redis running directory and copy the two running files to the past

Copy the configuration file to the past

3. Start the Redis service

Signs of successful front-end startup of the redis service

./redis-server

There is a problem at this time. The currently started one cannot be turned off. It will be gone once it is turned off, so it needs to be modified.

Stop the service Ctrl z

Stop the redis service first

Use the background to start the redis service

vim redis.conf

Change to yes to save and set Start redis in the background

Start again

I find that it is still started in the front end

Bring it on when starting Start the configuration file together

Check the redis process

It is found that redis has been started

4. Simple use

Three variables are set, and these three variables are stored in memory.

How to read?

Get!

5. Specific operations

1. Key operation

In redis, "\n" and spaces cannot be used as In addition to the component content of the name, other content can be used as the name part of the key. There is no requirement for the name length

In other words, it is the variable name

##DbsizeExpire key seconds Ttl key##Select db-indexMove key db-indexFlushdbFlushall

Code	Function
Exists key	Does it exist
Del key1 key2….	Delete the specified key
Type key	Returns the value type of the given key
Key pattern	Return all keys that match the specified pattern
##Rename oldkey newkey	Change name
##Return the number of keys in the current database
Specify the expiration time for the key
Returns the expiration seconds of key
Select database
Move key from the current database to the specified database
Delete all keys in the current database
Delete all keys in all databases

Here is an example of using it
2. String type operation

String is the most basic type of redis

Redis string can contain any data , including jpg pictures or serialized objects

The maximum limit of a single value is 1G bytes

Code##Set the value corresponding to the key to a string type value##Set the values ​​of multiple keys at onceGet the values ​​of multiple keys at one timeOperation on key value##Decr keySame as above – operation

Function

##Set key value

Mset key1 value1…keyN valueN

Mget key1 key2 … keyN

Incr key

##Incrby key integer

Same as incr plus specified value

Decrby key integer

Same as decr minus the specified value

Append key value

Append value to the string of the specified key

##Substr key start end

Return the string value of the intercepted key

3. Introduction and use of List linked list type

The List type is actually a doubly linked list

If you want to query The top 10 latest users,

have to be checked one by one, which consumes too many resources

List linked list example:

Through list The linked list stores the information of the latest 5 users who logged into the system

New users come in and old users are kicked out

How to operate the linked list?

Add a string element to the head of the list corresponding to the keyDeletes an element from the end of the list and returns the deleted element. If the key value does not exist, 0 is returned. If the corresponding type of key is not list returns error ##Rpush key string at the end Lpop keyLtrim key start end4. Set collection type

##Code	##Function
Lpush key string
Rpop key
Lien key returns the length of the list corresponding to key
Same as above, add
Deletes the element from the head of the list and returns the deleted element
Intercept the list and keep the elements in the specified range

Redis’ set is an unordered collection of string type.

Set elements can contain up to (2 to the 32nd power -1) elements

Each element in each set cannot be repeated

CodeFunctionSadd key memberSrem key memberSmove p1 p2 memberScard keySismember key memberSinter key1 key2.． . . Sunion key1 key2Sdiff key1 key2. Smembers key

There is a key with five elements in it

Then add a Linken

5. SortSet sorted set type operation

Like set, sorted set is also a collection of string elements

The difference is that each element is associated with a weight

The elements in the set can be obtained in order through the weight value

Case:

Use sort set to obtain the top 5 most popular posts for learning

Each element in the sorted set is a combination of value and weight

Add a string element to the set collection corresponding to key and return success 1
Removes the given element from the key corresponding set and returns 1 successfully
Remove member from the corresponding set of p1 and add it to the corresponding set of p2
Returns the number of elements in the set
Determine whether the member exists in the set
Returns the intersection of all given keys
Returns the union of all given keys
Return the difference set of all given keys
Returns all elements of the set corresponding to the key, and the result is unordered

Delete the specified element, 1 successful, 0 does not exist##Zincrby key incr member##Zrank key memberZrange key start endZrevrange key start endZcard keyZscore key elemet##Zremrangebyrank key min max

Code	Function
##Zadd key score member	Add elements to the collection, and update the corresponding score if the element exists in the collection
##Zrem key member
Increase the score value of the corresponding member according to the incr range and return the score value
Returns the ranking (subscript) of the specified element in the set. The elements in the set are sorted from small to large by score
Similar to the Irange operation, the elements in the specified range are specified from the collection, and the ordered results are returned
Same as above, the return is in reverse order
Returns the number of elements in the collection
Returns the score corresponding to the given element
#Delete the elements in the set that are ranked in the given point interval	6. Snapshot persistence It takes 900 seconds for one key change to be saved (snapshot) It takes 300 seconds for ten key changes to be saved ( Snapshot) Save Ten thousand key changes per minute (snapshot) Save The benefits of such control: The frequency of data modification is very high, and the frequency of backup is also high , The frequency of data modification is low, and the frequency of backup is also low. The name of the snapshot persistence ##Manually initiate snapshot persistence If for this machine: 7. AOF persistence Essence: Back up every "write" command (add, delete, modify) executed by the user to a file, and execute the specific "write" command when restoring Turning on AOF persistence will clear the inside of redis Data Enable AOF persistence The configuration file is modified and restart the service View the redis process: Ps – A | grep redis -9Force kill the process Start a new process Aof adds persistent backup frequency Always forces writing to the disk immediately after receiving a write command. It is very slow, but can maintain complete persistence. Everysec forces writing to the disk once per second. It has done a good job in terms of performance and persistence. A compromise, recommended No relies entirely on OS for the best performance, but persistence is not guaranteed 8. Master-slave mode In order to reduce the load of each redis server, you can set Several, and in master-slave mode One server load "writes" Other server loads "read" The master server will automatically synchronize to the slave server Modify IP address and port number

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