redis getting started

Redis playground...

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GitHub daggerok/redis-getting-started repository

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run database

run single node instance

docker run -d --rm --name redis redis:alpine

not shown: master-slaves approach

I this case you going to read from your slaves until you not restarted your master

also not shown: most reliable is run in sentinel mode

finally must have mode is clustered

create redis.conf file and start cluster

# change dir to safe place
cd /tmp/

# create redis config
cat << EOF > ./redis.conf
port 6379
cluster-enabled yes
cluster-config-file nodes.conf
cluster-node-timeout 5000
appendonly yes
EOF

# create docker network
docker network rm redis-net ; \
  docker network create redis-net

# run 6 redis nodes
for i in `seq 1 6`; do \
  docker run -d \
    --net redis-net --name redis-$i -p 6379 \
    -v $PWD/redis.conf:/usr/local/etc/redis/redis.conf \
    redis:alpine redis-server /usr/local/etc/redis/redis.conf; \
done

# find container ip
#for i in `seq 1 6`; do \
#  docker inspect -f '{{ (index .NetworkSettings.Networks "redis-net").IPAddress }}' redis-$i ; \
#done
# 172.26.0.2, 172.26.0.3, 172.26.0.4, 172.26.0.5, 172.26.0.6, 172.26.0.7

# build cluster node:port items list
export nodes=$(for i in `seq 1 6`; do \
  echo -n "$(docker inspect -f '{{ (index .NetworkSettings.Networks "redis-net").IPAddress }}' redis-$i):6379 " ; done)

# initialize redis cluster
echo 'yes' | docker exec -i redis-1 ash -c "\
  redis-cli --cluster create $nodes --cluster-replicas 1"

# connect with additional flag: '-c'
docker exec -it redis-4 redis-cli -c

# we can created keys and we will be redirected to proper node if needed
127.0.0.1:6379> set key-2 trololo
-> Redirected to slot [12422] located at 192.168.240.4:6379
OK
192.168.240.4:6379> set key-1 ololo
-> Redirected to slot [229] located at 192.168.240.2:6379
OK

# we can get key-1 or key-2 separately
192.168.240.2:6379> get key-1
"ololo"
192.168.240.2:6379> get key-2
-> Redirected to slot [12422] located at 192.168.240.4:6379
"troololo"

# but we cannot use mget for sharded data
192.168.240.4:6379> mget key-1 key-2
(error) CROSSSLOT Keys in request don't hash to the same slot
# so redis dose not serve cross slot data
# so spring data can help here us with that!
# spring-data can connect to all redis nodes to collect all info... 

::: tip Dont not create nodes.conf file. We don’t need to do anything except adding this line. :::

prepare redis-cli command alias fot using docker

function redis-cli { bash -c "docker exec -it redis ash -c 'redis-cli $1'"; }

basics

show keys keys

redis-cli 'keys *'
# (empty list or set)

set value set

redis-cli redis-cli 'set message hi'
# OK

get value get

redis-cli 'get message'
# "hi"
redis-cli 'keys *'
# 1) "message"

delete data del

redis-cli 'del message'
# (integer) 1

delete all data flushall

redis-cli redis-cli 'set k1 v1'
redis-cli redis-cli 'set k2 v2'
 
redis-cli 'keys *'
# 1) "k2"
# 2) "k1"
redis-cli 'flushall'
# OK
redis-cli 'keys \*' # escaping star... in real terminal, command should be: redis-cli keys *
# (empty list or set)

set value with expire of the key setex

redis-cli 'setex temporal 60 this-value-will-exire-after-60-secons'
# OK
redis-cli 'ttl temporal'
# (integer) 58
sleep 6s ; redis-cli 'get temporal'
# "this-value-will-exire-after-60-secons"
sleep 60s ; redis-cli 'get temporal'
# (nil)
redis-cli 'ttl temporal'
# (integer) -2

NOTE: if you wanna set expire in millis, use psetex command instead:

redis-cli 'psetex key milliseconds value'

set value if key is not available with setnx

redis-cli 'get new-key'
# (nil)
redis-cli 'setnx new-key a-value'
# (integer) 1
redis-cli 'get new-key'
# "a-value"
redis-cli 'setnx new-key this-value-wont-be-present'
# (integer) 0
redis-cli 'get new-key'
# "a-value"

get value size with strlen command

redis-cli 'set ololo trololo'
# OK
redis-cli 'strlen ololo'
# (integer) 7

setting multiple key-values

redis-cli 'flushall'
# OK
redis-cli 'mset k1 v1 k2 v2 k3 v3'
# OK
redis-cli 'keys \*'
# 1) "k3"
# 2) "k2"
# 3) "k1"

NOTE: command ttl stands for time to live

increment with incr and decrement with decr commands

redis-cli 'set salary 4444'
# OK
redis-cli 'decr salary'
# (integer) 4443
redis-cli 'incr salary'
# (integer) 4444
redis-cli 'incr salary'
# (integer) 4445

customize previous flow with incrby / decrby

redis-cli 'set salary 1000'
# OK
redis-cli 'decrby salary 5'
# (integer) 995
redis-cli 'incrby salary 500'
# (integer) 1495
redis-cli 'incrby salary 100500'
# (integer) 101995

append

redis-cli 'set message hello'
# OK
redis-cli 'append message -world!'
# (integer) 12
redis-cli 'get message'
# "hello-world!"

hashes

Why? Limitations for strings (key-value pairs) are about 512 Mb. But in case of hashes (field-value pairs) limits up to 4 billions field-value pairs

set key field-value pair with hmset

redis-cli 'hmset person username maksimko password very-secret'
# OK
redis-cli 'hget person password'
# "very-secret"
redis-cli 'hmget person password'
# 1) "very-secret"
redis-cli 'hgetall person'
# 1) "username"
# 2) "maksimko"
# 3) "password"
# 4) "very-secret"

hexists

redis-cli 'hexists person age'
# (integer) 0
redis-cli 'hexists person username'
# (integer) 1

age dose not exists in person object

hdel

redis-cli 'hdel person password'
# (integer) 1
redis-cli 'hgetall person'
# 1) "username"
# 2) "maksimko"

hsetnx

set field value if it's does not exists

redis-cli 'hsetnx person age 18' # will set new field
# (integer) 1
redis-cli 'hsetnx person age 19' # will ignore because age field already exists
# (integer) 0

hkeys

redis-cli 'hkeys person'
# 1) "username"
# 2) "age"

NOTE: returns only key fields of object

hincrby similar to strings

redis-cli 'hincrby person age 1'
# (integer) 19
redis-cli 'hincrby person age 5'
# (integer) 24

others

redis-cli 'hstrlen person username'
# (integer) 8
redis-cli  'hvals person'
# 1) "maksimko"
# 2) "24"
redis-cli 'hlen person' # number of fields in object hash
# (integer) 2
redis-cli 'hmget person username age'
# 1) "maksimko"
# 2) "24"

list

strings sorted in a some order

head <--> value1 <--> value2 <--> ... <--> valueN <--> tail

debug redis-cli

redis-cli 'monitor'

and do playground in a parallel terminal...

# create: my-list = List(3 2 1 0)
redis-cli 'lpush my-list 0 1 2 3'

# show first 10 elements of my-list moving from left to right
redis-cli 'lrange my-list 0 10'

# add 4 and 5 from left: List(5 4 3 2 1)
redis-cli 'lpush my-list 4 5'

# take out 1st left element ("5") from list: List(4 3 2 1)
redis-cli 'lpop my-list'

# update to palindrome: List(4 3 2 1 0 1 2 3 4)
redis-cli 'rpush my-list 0 1 2 3 4'

# show list items from 0th index till 10th index
redis-cli 'lrange my-list 0 10'

# show el of index 3 (4th element moving from left to right): "1"
redis-cli 'lindex my-list 3'

# set el in a middle to "X": List(4 3 2 1 X 1 2 3 4) 
redis-cli 'lset my-list 4 X'

# show whole list (from begin: 0, to last: -1)
redis-cli 'lrange my-list 0 -1'

# this will be not push because list does not exists 
redis-cli 'lpushx skip this one - it does not exists'

# but this will push both elements: List(6 5 4 3 2 1 X 1 2 3 4 5 6)
redis-cli 'lpushx my-list 5 6'
redis-cli 'rpushx my-list 5 6'

# insert XX to make XXX in a middle
redis-cli 'linsert my-list after X X' #  List(6 5 4 3 2 1 X X 1 2 3 4 5 6)
redis-cli 'linsert my-list before X X' # List(6 5 4 3 2 1 X X X 1 2 3 4 5 6)

sets

# create: my-set = Set(one two three)
redis-cli 'sadd my-set one two three'

# view
redis-cli 'smembers my-set'
# 1) "two"
# 2) "one"
# 3) "three"

redis-cli 'sadd my-other-set two three four'
redis-cli 'sdiff my-set my-other-set'
# 1) "one"
redis-cli 'sdiff my-other-set my-set'
# 1) "four"

redis-cli 'sunion my-other-set my-set'
# 1) "two"
# 2) "one"
# 3) "three"
# 4) "four"

redis-cli 'sunionstore result-set my-other-set my-set'
redis-cli 'smembers result-set'
# 1) "two"
# 2) "one"
# 3) "three"
# 4) "four"

redis-cli 'srem result-set four'
redis-cli 'smembers result-set'
# 1) "two"
# 2) "one"
# 3) "three"

# remove last value from result-set
redis-cli 'spop result-set'
# 3) "three"

redis-cli 'sadd result-set ololo trololo hohoho'
# remove random 2 values from result-set
redis-cli 'spop result-set 2'
# 1) "ololo"
# 2) "two"
redis-cli 'smembers result-set'
# 1) "one"
# 2) "hohoho"
# 3) "trololo"

also see: sinter - intersection and smove - move value from some set to another...

transactions

okay, enough...

cleanup

docker rm -f -v redis

build VuePress documentation

npm i ; npm run build

resources

• YouTube: Next Level Redis with Spring
• Redis cluster