Short Document
What ?
An In Memory Database
Why ?
Need for Speed
How ?
Store Key-Value data in memory for much faster access
When ?
Caching data in high demand
Large data crawling
Searching
Temporary information
Who ?
Backend developers, duh !
How To ?
I.Set a key and a value based on built-in data types (SET, LPUSH,..)
II.Get stored value by providing key
III.Possibly set a expiry timer in order to limit the storage shortage
IV.To limit access of bad people create users and set certain rule via ACL commands (ACL SETUSER … )
V. If your data is really important usingtransaction. (MULTI)
VI. Finally Backup configs and all database cause you know RAM, if you lose power, stored data and configs will be lost.
Which ?
Open Source
TCP connection
Written in ANSI-C , Scripting via Lua
Most of commands happens synced (Create a lock)
Few happens async (FLUSH, BGSAVE, UNLINK, …)
What if …
You want more than a simple key-value(data-types)?
String
> SET <key> <value> (EX : <seconds> ,PX : <miliseconds>)
> GET <key>
List : order is insertion
> LPUSH <key> <value> :key is a list and will append to head
> RPUSH <key> <value>:key is a list and will append to tail
> LRANGE <key> <int:start> <int:end> : get list by index
Set : unordered , unique
> SADD <key> <member>
> SMEMBERS <key> : get set
Hash : maps between string fields and string values
> HSET
> HGET
Sorted set : ordered by score, unique like set
Bitmap : Sting based with certain semantic to store image
HyperLogLogs: Sting based with certain semantic
Custom-DataType: You can create a custom data semantic ….
You are a team inside a company (authentication)?
> ACL (parameters) :access control list
List : show list of users
GetUser <username> : user params
SetUser <username> : create or update a user
on / off : enable of disable a user (default = off) ><password> : add a new password to user <<password> : remove this password if exists +<command> : add ability to use a specific command
> Auth <username> <password> : Well Signing up ...
You have multiple apps but one RAM ?
> SELECT <index> : chose from 15 different db, like namespaces, same thing just separated !
You are tired of a key (delete) ?
> DEL : delete a key
> UNLINK : delete a key
> EXISTS <key> <key> ... : check if a key is present (returns int : 0 not found , 1 or more means number of given keys that were available)
You need ACID ?
> MULTI : will create a queue of commands, So they will all execute correctly , or if error occurs none of them.
> EXEC :will execute given queue
> DISCARD : ifyou just not in the mood and want out …
You want ensourance (Backup)?
> SAVE : will save whole database in a file [sync]
> BGSAVE : will save whole database in a file [Async]
> LASTSAVE : check the unix time of last successful backup
> CONFIG GET dir :get directory of saved files
You are a big boy (mass data insertion)?
User pipe mode to feed data into redis db like so :
$ cat data.txt | redis-cli –pipe
The text should include redis protocol in order to parse file in ASCII format
"*3\r\n$3\r\nSET\r\n$3\r\nGreeting\r\n$5\r\nHello\r\n"
Which translates to :
>SET Greeting Hello
You are board ?
> LOLWUT : will show you cheer you up
You are mad (want everything gone) ?
>FLUSHALL : removes all keys everywhere …
>FLUSHDB :removes all keys in selected db(1-15)…
You want more ?
Simple my friend, go visit Redis Commandsfor much more information and in depth explanations.
OH Wait …
INSTALATION :
$ Sudo apt install redis ( Job Done ! )
I’d be sad if you try this in command line cause it doesn’t work :(((
