Redis-In-Depth

Introduction
Basic
Keys
Shutdown
String
List
Hash

introduction

In memmory DB
NoSQL DB (key-val store)
Caching & message broker (communication between client & application)
Written in ANSI C
Stores data in ram rather than hard disk
It supports data structures like: str, hash, list, sort, set, sorted set with range queries, bitmaps, hyperloglogs.

basic

key type
```
type key
```
set key val
```
set key val
```
set multiple key val
```
set key1 val1 key2 val2 key3 val3 ...
```

set key val if not exists

// for single key-val

set key1 val1 nx

// for multiple key-val

msetnx key1 val1 key2 val2 key3 val3 ...

overwite val if only the key exists

// for single key-val

set key1 val1 xx

set expiration

set key val ex 10   // key will expire in 10 sec
ttl key             // how many sec are left to expire
persist key         // remove expiration

get val
```
get key
```
get multiple key val
```
mget key1 key2 key3 ...
```

replace oldVal

// replace oldVal with newVal

getset key val

save data
```
dump key
```
del key
```
del key
del key1 key2 key...n
```
exist key
```
exists key
exists key1 key2 key...n
```
restore data
```
restore key 0 serialized-value
```
append data in key
```
append key val
```

increment value of a key ( must be int )

// by default the value will be incremented by 1

incr key

// custom val to increment

incrby key value
incrbyfloat key value

derement value of a key ( must be int )

// by default the value will be decremented by 1

decr key

// custom val to decrement

decrby key value

keys

set some keys as example

set hallo 1
set hello 2
set hrllo 3
set heello 4
set hijkllo 5

keys pattern

keys h?llo      // keys with length 5:hallo,hello,hrllo
keys h*llo      // keys with any length
keys h[a-r]llo  // keys between a to r that postion: hallo, hello, hrllo
keys h[ae]llo   // keys with a or r:hallo,hello
keys h[^e]llo   // keys except e char
keys *l*        // any keys contains i
keys h????      // keys with 5 char starting with h
keys ?????      // any key with length 5

keys cmd

keys *                  // list of keys
randomkey               // any random key
rename oldKey newkey    //reanme key  
unlink key              // del key asynchronously without blocking current thread. Faster than del & useful for large data.  
type key                // key datatype

shutdown

save/unsave data on disk

shutdown save/nosave    // save/nosave:optional

string

slice

// upper limit inclusive

getrange key startPos endPos
getrange key 0 5

// -1: last pos

getrange key startPos endPos
getrange key 0 -1
getrange key -3 -1

replace by pos
```
setrange key pos val
```

list

Redis list is implemented by LinkedList.

lpush

// last element will be 1st one

lpush key val1 val2 val3 ... valn

rpush

// last element will be last one

rpush key val1 val2 val3 ... valn

get list
```
lrange key startPos endPos
```

push val if key exists

// last element will be last one

lpushx key val1 val2 val3 ... valn
rpushx key val1 val2 val3 ... valn

remove element

// remove element from left side
lpop key

// remove element from right side
rpop key

// remove all element except these range
ltrim key startPos endPos
ltrim key 1 -2

remove element by cond

// remove that particular element from list
lrem key 0 val

change the element by pos
```
lset key index val
```
get the element by pos
```
lindex key index
```

insert val in list

linsert key before/after matchingVal newVal

hash

every hash can store up to 2³²-1 field-val pairs(more than 4 billion)

set one field val

// if field exists then update otherwise insert

hset key field value
// ex: hset student name samrat

set multiple field val

hmset key field1 value1 field2 value2 field...n value...n

// ex: hmset student name samrat profession "Data Engineer"

get one val

hget key field

// ex: hset student name
// output: samrat

get multiple val

hmget key field1 field2 field...n

// ex: hmget student name profession
// output: samrat "Data Engineer"

get all keys
```
hkeys key
```

get all val

hvals key

// ex: hvals student
// output: all val

get all field-val
```
hgetall key
```
check field exists or not
```
hexists key field
```
length of key
```
hlen key
```
length of particular field
```
hstrlen key field
```
insert field if not exists
```
hsetnx key field value
```
delete field
```
hdel key field1 field2 field...n
```

increment field val ( must be int/float )

// only int type
hincrby key field val increment

// can be used in both float and int type
hincrbyfloat key field val increment