Exploring redis commands - part 1

The first thing to do in order to check if Redis is working properly is sending a PING command using redis-cli:

    127.0.0.1:6379> ping
    PONG

saving key & retreving saved value

    127.0.0.1:6379> set mykey myvalue
    OK

    127.0.0.1:6379> get mykey
    "myvalue"
    127.0.0.1:6379>

setting password
    open "/etc/redis/redis.conf" and look for "requirepass" commented line,uncomment it set password as
    requirepass sangram

    then we need to restart service

         sudo service redis-server restart .now we need to open redis-cli again
on redis-cli we will check password is enforced or not,lets try to set some random key value as follows

    127.0.0.1:6379> set mykey test
    (error) NOAUTH Authentication required.

Now we will keyin password as follows
    127.0.0.1:6379> auth sangram
    OK
after getting authenticated we are able to save key

    127.0.0.1:6379> set mykey test
    OK
Getting config value
    127.0.0.1:6379> config get requirepass
    1) "requirepass"
    2) "sangram"

Overrride key
    127.0.0.1:6379> set mykey test2
    OK
    127.0.0.1:6379> get mykey
    "test2"
Deleteing key:
    127.0.0.1:6379> DEL mykey
    (integer) 1
List keys by pattern:
    127.0.0.1:6379> set mykey1 test2
    OK
    127.0.0.1:6379> set mykey2 test2
    OK
    127.0.0.1:6379> KEYS my*
    1) "mykey2"
    2) "mykey"
    3) "mykey1

List All Keys:
    127.0.0.1:6379> KEYS *
    1) "mykey2"
    2) "mykey"
    3) "mykey1"

Expiry:
    Redis Expire command is used to set the expiry of a key. After the expiry time, the key will not be available in Redis.It returns 1, if timeout is set for the key else 0.

    127.0.0.1:6379>  EXPIRE mykey 10
    (integer) 1
     unit of expiry time is in seconds

    checking if key expired
    127.0.0.1:6379> KEYS *
    1) "mykey1"
    2) "mykey2"
    3) "\xe2\x80\x9ca-test\xe2\x80\x9d"
    4) "a-test"

     no occurance of mykey found.

     setting key in milli seconds

    127.0.0.1:6379> set mykey3 test3 PX 5000
    OK


we can also set expiry at the time of adding key

    127.0.0.1:6379> set mykey3 test3 EX 10
    OK

Check if key exist:returns 1 if key exist else 0.
    127.0.0.1:6379> EXISTS mykey3
    (integer) 0

    127.0.0.1:6379> EXISTS mykey1
    (integer) 1

Store Javascript objects in Redis

    127.0.0.1:6379> HSET "a-test" "name.first" "Kyle"
    (integer) 1
    127.0.0.1:6379> HSET "a-test" "name.family" "Davis"
    (integer) 1
    127.0.0.1:6379> HSET "a-test" "address" "123 Main Street"
    (integer) 1

    Get value for saved key:

        127.0.0.1:6379> HGET "a-test" "name.family"
        "Davis"
        127.0.0.1:6379> HGET "a-test" "address"
        "123 Main Street"

         Get value for saved keys:
        127.0.0.1:6379> HMGET "a-test" "name.first" "address"
        1) "Kyle"
        2) "123 Main Street"


     this is same as saving below json in javascript world

    var aTest = {
        "name.first" : ‘Kyle’,
        "name.family" : ‘Davis’,
        "address" : ‘123 Main Street’
      }

    Storing multiple key at in one go:

        127.0.0.1:6379> HMSET adrees city "mumbai" zip "400074"
        OK
        127.0.0.1:6379> HGET adrees city
        "mumbai"

    add key only if key does not exist do not override existing key value

        127.0.0.1:6379> HSETNX adrees city "pune"
        (integer) 0
        127.0.0.1:6379> HSETNX adrees state "maharshtra"
        (integer) 1

    confirming insertion:
        127.0.0.1:6379> HGETALL adrees
        1) "city"
        2) "mumbai"
        3) "zip"
        4) "400074"
        5) "state"
        6) "maharshtra"

       removing key:

        127.0.0.1:6379> HDEL "a-test" "name.family"
        (integer) 1

       view complete hash:

        127.0.0.1:6379> HGETALL "a-test"
        1) "name.first"
        2) "Kyle"
        3) "address"
        4) "123 Main Street"

    list all keys only

        127.0.0.1:6379> HKEYS "a-test"
        1) "name.first"
        2) "address"

    list all values:
        127.0.0.1:6379> HVALS a-test
        1) "Kyle"
        2) "123 Main Street"

    total keys:
        127.0.0.1:6379> HLEN "a-test"
        (integer) 2

    check key exist in hash:
        127.0.0.1:6379> HEXISTS "a-test"  address
        (integer) 1
        127.0.0.1:6379> HEXISTS "a-test"  addresss
        (integer) 0

  
Database:
    In Redis the number of Redis databases is fixed, and set in the configuration file. By default, you have 16 databases. Each database is identified by a number (not a name).

    You can use the following command to know the number of databases:

    127.0.0.1:6379> CONFIG GET databases
    1) "databases"
    2) "16"

       selecting database of specific number

        127.0.0.1:6379> select 1
        OK
        127.0.0.1:6379[1]> set mykey3 test3
        OK
        127.0.0.1:6379[1]> KEYS *
        1) "mykey3"

      on redis-cli switching between databases the key persist.


You can use the following command to list the databases for which some keys are defined:

    127.0.0.1:6379> INFO keyspace
    # Keyspace
    db0:keys=4,expires=0,avg_ttl=0

To get redis backup dir
    127.0.0.1:6379> CONFIG get dir
    1) "dir"
    2) "/var/lib/redis"

Redis SAVE command is used to create a backup of the current Redis database.

    127.0.0.1:6379> SAVE
    OK

    This command will create a dump.rdb file in your Redis directory.

    root@sangram-HP-Laptop-15-bs0xx:/home/sangram/workspace/node/hoisting# ls -lth /var/lib/redis/dump.rdb
    -rw-rw---- 1 redis redis 358 Sep 22 20:24 /var/lib/redis/dump.rdb

       Notice time file has been created.


    BGSAVE command will start the backup process and run this in the background.

    127.0.0.1:6379> BGSAVE
    Background saving started

To restore Redis data, move Redis backup file (dump.rdb) into your Redis backup directory and start the server.