Table of contents
- [GITHUB REPO] (https://github.com/Subham-Maity/fullstack_advance/tree/main/5.redis)
- Covered Topics
- Introduction:
- Installation:
- Redis CLI Commands:
- Nodejs Setup
- Time complexity, Limitations, Use cases
- Data Types
- String Data Structure:
- List Data Structure:
- Set Data Structure:
- Set Operations
- Cli Commands
- 3.1.SADD
- 3.2.SREM
- 3.3.SISMEMBER
- 3.4.SMEMBERS
- 3.5.SPOP
- 3.6.SRANDMEMBER
- 3.7.SMOVE
- 3.8.SCARD
- 3.9.SINTER
- 3.10.SUNION
- 3.11.SDIFF
- 3.12.SINTERSTORE
- 3.13.SUNIONSTORE
- 3.14.SDIFFSTORE
- 3.15.SSCAN
- Hash Data Structure:
- Cli Commands
- 4.1.HSET
- 4.2.HGET
- 4.3.HGETALL
- 4.4.HDEL
- 4.5.HEXISTS
- 4.6.HKEYS
- 4.7.HVALS
- 4.8.HLEN
- 4.9.HINCRBY
- 4.10.HINCRBYFLOAT
- 4.11.HMSET
- 4.12.HMGET
- 4.13.HSETNX
- 4.14.HSTRLEN
- 4.15.HSCAN
- Sorted Set Operations with Redis
- Sorted Set Operations
- Cli Commands
- 5.1.ZADD
- 5.2.ZREM
- 5.3.ZSCORE
- 5.4.ZRANGE
- 5.5.ZREVRANGE
- 5.6.ZRANGEBYSCORE
- 5.7.ZREVRANGEBYSCORE
- 5.8.ZCARD
- 5.9.ZCOUNT
- 5.10.ZINCRBY
- 5.11.ZLEXCOUNT
- 5.12.ZRANGEBYLEX
- 5.13.ZREVRANGEBYLEX
- 5.14.ZREMRANGEBYLEX
- 5.15.ZREMRANGEBYRANK
- 5.16.ZREMRANGEBYSCORE
- 5.17.ZUNIONSTORE
- 5.18.ZINTERSTORE
- 5.19.ZSCAN
- 5.20.ZRANK
- REDIS STREAMS OPERATIONS
- Redis Bitmaps
- Geospatial Operations
- Probabilistic Data Structures
- Time Series Data Structures
- Pub/Sub
- Scale A Node.js Application With Redis
If you want to see more of my work, you can follow me on LinkedIn, GitHub, Dev , Hashnode I post regularly about web development, data fetching, and other topics. 🚀
Covered Topics
What is Redis?
How to set up Redis with docker? (redis-stack and redis-client)
CLI commands for Redis
Redis with Node.js
Data Types
String Operations (cli and node.js) →
set name,get name,setnx,MSET,MGET,INCR,INCRBY,GETRANGE,SETRANGE,GETRANGE,STRLEN,APPEND,SETEX,SETNX,MSETNX,SETRANGE,GETRANGE,STRLEN,DECR,DECRBY,PSETEXList Operations (cli and node.js) →
LPUSH(Stack & Queue Concept),RPUSH(Stack & Queue Concept),LPOP,RPOP,LLEN,LRANGE,LINDEX,LINSERT,LSET,LTRIM,LREM,RPOPLPUSH,BLPOP,BRPOP,BRPOPLPUSHSet Operations (cli and node.js) →
SADD,SREM,SISMEMBER,SMEMBERS,SPOP,SRANDMEMBER,SMOVE,SCARD,SINTER,SUNION,SDIFF,SDIFF,SINTERSTORE,SUNIONSTORE,SDIFFSTORE,SSCANHash Operations (cli and node.js) →
HSET,HGET,HGETALL,HDEL,HEXISTS,HKEYS,HVALS,HLEN,HINCRBY,HINCRBYFLOAT,HMSET,HMGET,HSETNX,HSTRLEN,HSCANSorted Set Operations (cli and node.js) →
ZADD,ZREM,ZSCORE,ZRANGE,ZREVRANGE,ZRANGEBYSCORE,ZREVRANGEBYSCORE,ZCARD,ZCOUNT,ZINCRBY,ZLEXCOUNT,ZRANGEBYLEX,ZREVRANGEBYLEX,ZREMRANGEBYLEX,ZREMRANGEBYRANK,ZREMRANGEBYSCORE,ZUNIONSTORE,ZINTERSTORE,ZSCAN,ZPOPMIN,ZPOPMAX,BZPOPMIN,BZPOPMAX,ZRANKREDIS STREAMS OPERATIONS (cli and node.js) →
XADD,XLEN,XRANGE,XREVRANGE,XREAD,XREADGROUP,XGROUP,XACK,XCLAIM,XDEL,XTRIM,XINFO,XSETID,XREWRITEBitmaps Operations (cli and node.js) →
GEOADD,GEOPOS,GEODIST,GEORADIUS,GEORADIUSBYMEMBER,GEOHASH,GEOSEARCH,GEOSEARCHSTORE
Redis Pub/Sub
Scale A Node.js Application with Redis
Introduction:
Redis is an open-source, in-memory key-value data store. It is versatile and can be used as a database, cache, and message broker. Redis supports various data structures such as Strings, Hashes, Lists, Sets, and more. It provides high availability via Redis Sentinel and automatic partitioning across multiple Redis nodes with Redis Cluster.
Installation:
Download Docker Desktop from the official Docker website.
Install Docker Desktop and open it.
Open the terminal and run the following command to start the Redis server and Redis Commander:
docker run -d --name redis-stack -p 6379:6379 -p 8001:8001 redis/redis-stack:latest
This command will run the Redis server on port 6379 and Redis Commander on port 8001.
Open a web browser and navigate to
localhost:8001to view the Redis Commander.Go back to the terminal and run
docker psto check if the Redis server is running. If it's not, rundocker start redis-stack.
Now, you can use the Redis server in your project.
Redis CLI Commands:
Run
docker psin the terminal to check the running container and copy the container id.Use
docker exec -it <container_id> bashto open the bash terminal of the container. For example:docker exec -it 7b7e bash.Type
redis-clito open the Redis CLI terminal.Type
pingto check if the Redis server is running. If you getPONG, then the server is running.
Nodejs Setup
- open the 5.redis folder and run the following command
npm run string
npm run list
npm run set
npm run hash
npm run sortedset
npm run stream
npm run bitmap
npm run geo
npm run pubsub
npm run dev
- open the server/src/client.ts setup the redis client
import Redis from "ioredis";
const client = new Redis({
host: 'localhost', // replace with your host, if not localhost
port: 6379 // replace with your port, if not 6379
});
export default client;
- open the 5.redis folder and you will get the following files
string.ts
list.ts
set.ts
hash.ts
sortedset.ts
stream.ts
bitmap.ts
geo.ts
pubsub.ts
src/client.ts
src/todos.ts
Time complexity, Limitations, Use cases
Time Complexity
Hashes: O(1) for each key-value pair, O(N) for N key-value pairs.
Lists: O(1) for each push/pop operation, O(N) for N items in the list.
Sets: O(1) for each add/remove operation, O(N) for N items in the set.
Sorted Sets: O(1) for each add/remove operation, O(log(N)+M) for N items in the sorted set and M elements returned.
Streams: O(1) for each item added to the stream, O(N) for N items in the stream.
Bitmaps: O(1) for each set bit, O(N) for N bits set.
Geo: O(log(N)) for each item added to the sorted set, where N is the number of elements in the sorted set.
Pub/Sub: O(N+M) for N channels and M subscribers.
Limitations
Hashes: The maximum number of fields is (2^32 - 1)4294967295, more than 4 billion of fields per hash).
Lists: The maximum number of elements is (2^32 - 1)4294967295, more than 4 billion of elements per list).
Sets: The maximum number of members is (2^32 - 1)4294967295, more than 4 billion of elements per set).
Sorted Sets: The maximum number of members is (2^32 - 1)4294967295, more than 4 billion of elements per sorted set).
Streams: The maximum number of entries is (2^64 - 1)18446744073709551615, more than 18 quintillion of entries per stream).
Bitmaps: The maximum number of bits is (2^32 - 1)4294967295, more than 4 billion of bits per bitmap).
geo: The maximum number of members is (2^32 - 1)4294967295, more than 4 billion of elements per geo set).
Pub/Sub: The maximum number of channels is 2^32 - 1)4294967295, more than 4 billion of channels per Redis instance).
Use cases
Redis hash—Use hashes when you have a large number of fields to store. For example, you can use hashes to store user information, such as name, email, address, and more.
Redis list—Use lists when you want to store a list of items. For example, you can use lists to store a list of products, a list of users, and more.
Redis set—Use sets when you want to store a unique list of items. For example, you can use sets to store a list of tags, a list of followers, and more.
Redis sorted set—Use sorted sets when you want to store a list of items in a sorted order. For example, you can use sorted sets to store a list of products sorted by price, a list of users sorted by age, and more.
Redis stream—Use streams when you want to store a list of items in a chronological order. For example, you can use streams to store a list of events, a list of messages, and more.
Bitmap — Use bitmaps when you want to store a list of items in a chronological order. For example, you can use bitmaps to store a list of events, a list of messages, and more.
Geo — Use geo when you want to store a list of items in a chronological order. For example, you can use geo to store a list of events, a list of messages, longitudes, latitudes, and more.
Pub/Sub — Use pub/sub when you want to store a list of items in a chronological order. For example, you can use pub/sub to store a list of events, a list of messages, and more.
Data Types
String Data Structure:
Cli Commands
1.1.set name
Type set name "subham" to set a key-value pair in the Redis server.
1.2.get name
Type get name to retrieve the value of the key from the Redis server.
Note: If you open your Redis stack in the browser, you will see the key and value set. You can also update the value from there. Just click on the key and update the value on the right side. The Best way to do this is
set user:1 "subham"
set user:2 "codexam"
set user:3 "xamcodexam"
set msg:1 "hello"
set msg:2 "hi"
set msg:3 "hey"
If you group on the redis-stack you will see the data like this
user
1: "subham"
2: "codexam"
3: "xamcodexam"
msg
1: "hello"
2: "hi"
3: "hey"
1.3.setnx
set if not exists(nx)
set user:1 "subham" nx
if you don't use nx, then it will overwrite the value
set user:1 "codexam"
1.4.MSET
set multiple values
mset user:1 "subham" user:2 "codexam" msg:1 "hello" msg:2 "hi"
1.5.MGET
get multiple values
mget user:1 user:2 msg:1 msg:2
1) "subham"
2) "codexam"
3) "hello"
4) "hi"
1.6.INCR
increment the value by 1
set user:1 10
incr user:1
(integer) 11
1.7.INCRBY
increment the value by 5
set user:1 10
incrby user:1 5
(integer) 15
Note: By default a single Redis string can be a maximum of 512MB in size.
1.8.GETRANGE
get the value from the range(SUBSTRING)
set user:1 "subham"
getrange user:1 0 3
"subh"
1.9.SETRANGE
set the value from the range(SUBSTRING)
set user:1 "subham"
setrange user:1 0 "codexam"
(integer) 7
get user:1
"codexam"
1.10.GETRANGE
get the value from the range(SUBSTRING)
set user:1 "subham"
getrange user:1 0 3
"subh"
1.11.STRLEN
get the length of the value
set user:1 "subham"
strlen user:1
(integer) 6
1.12.APPEND
append the value
set user:1 "subham"
append user:1 " codexam"
(integer) 14
get user:1
"subham codexam"
1.13.SETEX
set the value with expiration time (in seconds)
setex user:1 10 "subham"
(integer) 1
get user:1
"subham"
get user:1
(nil)
1.14.SETNX
set the value if the key doesn't exist
setnx user:1 "subham"
(integer) 1
get user:1
"subham"
setnx user:1 "codexam"
(integer) 0
get user:1
"subham"
1.15.MSETNX
set multiple values if the key doesn't exist
msetnx user:1 "subham" user:2 "codexam" msg:1 "hello" msg:2 "hi"
(integer) 1
get user:1
"subham"
get user:2
"codexam"
get msg:1
"hello"
get msg:2
"hi"
1.16.SETRANGE
set the value from the range(SUBSTRING)
set user:1 "subham"
setrange user:1 0 "codexam"
(integer) 7
get user:1
"codexam"
1.17.GETRANGE
get the value from the range(SUBSTRING)
set user:1 "subham"
getrange user:1 0 3
"subh"
1.18.STRLEN
get the length of the value
set user:1 "subham"
strlen user:1
(integer) 6
1.19.DECR
This command decreases the value of a key by 1. If the key does not exist, it is set to -1.
set user:1 10
decr user:1
(integer) 9
1.20.DECRBY
This command decreases the value of a key by the given number. If the key does not exist, it is set to negative the given number.
set user:1 10
decrby user:1 5
(integer) 5
1.21.PSETEX
This command sets the value and expiration in milliseconds of a key.
psetex user:1 10000 "subham"
(integer) 1
get user:1
"subham"
get user:1
(nil)
List Data Structure:
A list data structure is a collection of elements in the order they are inserted. It is similar to an array in other programming languages. The list data structure is often used to implement other data structures like queues and stacks.
List Operations
Here are some operations performed on a list:
| Operation | Element |
| Push | 1 |
| Push | 2 |
| Push | 3 |
| Pop | 3 |
| Pop | 2 |
| Pop | 1 |
Cli Commands
2.1.LPUSH
This command inserts the specified value at the head of the list.
lpush user:1 "subham"
lpush user:1 "codexam"
Visualize the list in the Redis Commander. Last In First Out (LIFO) (similar to stack)
| Index | Element |
| 0 | codexam |
| 1 | subham |
2.2.RPUSH
This command inserts the specified value at the tail of the list.
rpush user:1 "subham"
rpush user:1 "codexam"
Visualize the list in the Redis Commander.
| Index | Element |
| 0 | subham |
| 1 | codexam |
Note
Redis can be used to implement a stack data structure, which follows a Last In, First Out (LIFO) principle. You can use the lpush command to insert elements at the head of the list, and the lpop command to remove elements from the head of the list.
Here's an example of how you can use Redis commands to implement a stack:
lpush user:1 "subham"
lpush user:1 "codexam"
lpop user:1 # Output: "codexam"
lpop user:1 # Output: "subham"
Visualization in Redis Commander
- After
lpushoperations:
| Index | Element |
| 0 | codexam |
| 1 | subham |
- After first
lpopoperation:
| Index | Element |
| 0 | subham |
- After second
lpopoperation:
| Index | Element |
As you can see, the last element pushed to the stack is the first one to be popped, which is characteristic of a stack.
2.3.LPOP
This command removes and returns the first element of the list.
lpush user:1 "subham"
lpush user:1 "codexam"
lpop user:1
"codexam"
2.4.RPOP
This command removes and returns the last element of the list.
lpush user:1 "subham"
lpush user:1 "codexam"
rpop user:1
"subham"
2.5.LLEN
This command returns the length of the list.
lpush user:1 "subham"
lpush user:1 "codexam"
llen user:1
(integer) 2
2.6.LRANGE
This command returns the specified range of elements from the list.
lpush user:1 "subham"
lpush user:1 "codexam"
lrange user:1 0 1
1) "codexam"
2) "subham"
2.7.LINDEX
This command returns the element at the specified index.
lpush user:1 "subham"
lpush user:1 "codexam"
lindex user:1 0
"codexam"
2.8.LSET
This command sets the value at the specified index.
lpush user:1 "subham"
lpush user:1 "codexam"
lset user:1 0 "xamcodexam"
"OK"
lrange user:1 0 1
1) "xamcodexam"
2) "subham"
2.9.LINSERT
This command inserts the specified value before or after the specified pivot value.
lpush user:1 "subham"
lpush user:1 "codexam"
linsert user:1 before "subham" "xamcodexam"
(integer) 3
lrange user:1 0 1
1) "codexam"
2) "xamcodexam"
3) "subham"
2.10.LSET
This command sets the value at the specified index.
lpush user:1 "subham"
lpush user:1 "codexam"
lset user:1 0 "xamcodexam"
"OK"
lrange user:1 0 1
1) "xamcodexam"
2) "subham"
2.11.LTRIM
This command trims the list to the specified range.
lpush user:1 "subham"
lpush user:1 "codexam"
ltrim user:1 0 1
"OK"
lrange user:1 0 1
1) "codexam"
2) "subham"
2.12.LREM
This command removes the specified number of occurrences of the specified value from the list.
lpush user:1 "subham"
lpush user:1 "codexam"
lpush user:1 "subham"
lpush user:1 "codexam"
lrem user:1 2 "subham"
(integer) 2
lrange user:1 0 1
1) "codexam"
2) "codexam"
2.13.RPOPLPUSH
This command removes the last element from the source list and pushes it to the destination list.
lpush user:1 "subham"
lpush user:1 "codexam"
rpoplpush user:1 user:2
"subham"
lrange user:1 0 1
1) "codexam"
lrange user:2 0 1
1) "subham"
2.14.BRPOP
This command is similar to rpop, but it blocks the connection until an element is available or the timeout is reached.
lpush user:1 "subham"
lpush user:1 "codexam"
brpop user:1 10
1) "user:1"
2) "codexam"
It will block the connection for 10 seconds and then return the element. If no element is available, it will return nil.
2.15.BLPOP
This command is similar to lpop, but it blocks the connection until an element is available or the timeout is reached.
lpush user:1 "subham"
lpush user:1 "codexam"
blpop user:1 10
1) "user:1"
2) "codexam"
It will block the connection for 10 seconds and then return the element. If no element is available, it will return nil.
2.16.BRPOPLPUSH
This command is similar to rpoplpush, but it blocks the connection until an element is available or the timeout is reached.
lpush user:1 "subham"
lpush user:1 "codexam"
brpoplpush user:1 user:2 10
"subham"
It will block the connection for 10 seconds and then return the element. If no element is available, it will return nil.
Set Data Structure:
A set data structure is a collection of unordered, unique elements. It is similar to a set in mathematics. The set data structure is often used to implement other data structures like queues and stacks.
Set Operations
Here are some operations performed on a set:
| Operation | Element |
| Add | 1 |
| Add | 2 |
| Add | 3 |
| Remove | 3 |
| Remove | 2 |
| Remove | 1 |
Cli Commands
3.1.SADD
This command adds the specified member to the set.
sadd user:1 "subham"
sadd user:1 "codexam"
sadd user:1 "subham"
smembers user:1
1) "subham"
2) "codexam"
Visualize the set in the Redis Commander.
| Index | Element |
| 0 | subham |
| 1 | codexam |
3.2.SREM
This command removes the specified member from the set.
sadd user:1 "subham"
sadd user:1 "codexam"
srem user:1 "subham"
smembers user:1
1) "codexam"
3.3.SISMEMBER
This command checks if the specified member is present in the set.
sadd user:1 "subham"
sadd user:1 "codexam"
sismember user:1 "subham"
(integer) 1
3.4.SMEMBERS
This command returns all the members of the set.
sadd user:1 "subham"
sadd user:1 "codexam"
smembers user:1
1) "subham"
2) "codexam"
3.5.SPOP
This command removes and returns a random member from the set.
sadd user:1 "subham"
sadd user:1 "codexam"
spop user:1
"codexam"
3.6.SRANDMEMBER
This command returns a random member from the set.
sadd user:1 "subham"
sadd user:1 "codexam"
srandmember user:1
"codexam"
3.7.SMOVE
This command moves the specified member from one set to another.
sadd user:1 "subham"
sadd user:1 "codexam"
sadd user:2 "xamcodexam"
smove user:1 user:2 "subham"
smembers user:1
1) "codexam"
smembers user:2
1) "xamcodexam"
2) "subham"
3.8.SCARD
This command returns the number of members in the set.
sadd user:1 "subham"
sadd user:1 "codexam"
scard user:1
(integer) 2
3.9.SINTER
This command returns the intersection of all the sets specified.
sadd user:1 "subham"
sadd user:1 "codexam"
sadd user:2 "xamcodexam"
sinter user:1 user:2
1) "subham"
3.10.SUNION
This command returns the union of all the sets specified.
sadd user:1 "subham"
sadd user:1 "codexam"
sadd user:2 "xamcodexam"
sunion user:1 user:2
1) "subham"
2) "codexam"
3) "xamcodexam"
3.11.SDIFF
This command returns the difference between the first set and all the other sets specified.
sadd user:1 "subham"
sadd user:1 "codexam"
sadd user:2 "xamcodexam"
sdiff user:1 user:2
1) "codexam"
3.12.SINTERSTORE
This command stores the intersection of all the sets specified.
sadd user:1 "subham"
sadd user:1 "codexam"
sadd user:2 "xamcodexam"
sinterstore user:3 user:1 user:2
(integer) 1
smembers user:3
1) "subham"
3.13.SUNIONSTORE
This command stores the union of all the sets specified.
sadd user:1 "subham"
sadd user:1 "codexam"
sadd user:2 "xamcodexam"
sunionstore user:3 user:1 user:2
(integer) 3
smembers user:3
1) "subham"
2) "codexam"
3) "xamcodexam"
3.14.SDIFFSTORE
This command stores the difference between the first set and all the other sets specified.
sadd user:1 "subham"
sadd user:1 "codexam"
sadd user:2 "xamcodexam"
sdiffstore user:3 user:1 user:2
(integer) 1
3.15.SSCAN
This command scans the set for members matching the specified pattern.
sadd user:1 "subham"
sadd user:1 "codexam"
sscan user:1 0 match "sub*"
1) "0"
2) 1) "subham"
Hash Data Structure:
A hash data structure is a collection of key-value pairs. It is similar to a hash table in other programming languages. The hash data structure is often used to implement other data structures like queues and stacks.
Cli Commands
4.1.HSET
This command sets the specified field in the hash to the specified value.
hset user:1 name "subham"
hset user:1 email "subham@gmail.com"
Visualize the hash in the Redis Commander.
| Field | Value |
| name | subham |
| codexam |
4.2.HGET
This command returns the value of the specified field in the hash.
hset user:1 name "subham"
hset user:1 email "
hget user:1 name
"subham"
4.3.HGETALL
This command returns all the fields and values of the hash.
hset user:1 name "subham"
hset user:1 email "subham@gmail.com"
hgetall user:1
1) "name"
2) "subham"
3) "email"
4) "subham@gmail.com"
4.4.HDEL
This command deletes the specified field from the hash.
hset user:1 name "subham"
hset user:1 email "subham@gmail.com"
hdel user:1 email
(integer) 1
hgetall user:1
1) "name"
2) "subham"
4.5.HEXISTS
This command checks if the specified field exists in the hash.
hset user:1 name "subham"
hset user:1 role "admin"
hexists user:1 role
(integer) 1
4.6.HKEYS
This command returns all the fields of the hash.
hset user:1 name "subham"
hset user:1 role "admin"
hkeys user:1
1) "name"
2) "role"
4.7.HVALS
This command returns all the values of the hash.
hset user:1 name "subham"
hset user:1 role "admin"
hvals user:1
1) "subham"
2) "admin"
4.8.HLEN
This command returns the number of fields in the hash.
hset user:1 name "subham"
hset user:1 role "admin"
hlen user:1
(integer) 2
4.9.HINCRBY
This command increments the specified field by the specified value.
hset user:1 age 20
hincrby user:1 age 5
(integer) 25
4.10.HINCRBYFLOAT
This command increments the specified field by the specified value.
hset user:1 age 20
hincrbyfloat user:1 age 5.5
"25.5"
4.11.HMSET
This command sets the specified fields to their respective values in the hash.
hmset user:1 name "subham" role "admin"
hgetall user:1
1) "name"
2) "subham"
3) "role"
4) "admin"
4.12.HMGET
This command returns the values of the specified fields in the hash.
hmset user:1 name "subham" role "admin"
hmget user:1 name role
1) "subham"
2) "admin"
4.13.HSETNX
This command sets the specified field to the specified value if the field does not exist in the hash.
hsetnx user:1 name "subham"
hsetnx user:1 name "codexam"
(integer) 0
4.14.HSTRLEN
This command returns the length of the value of the specified field in the hash.
hset user:1 name "subham"
hstrlen user:1 name
(integer) 6
4.15.HSCAN
This command scans the hash for fields matching the specified pattern.
hset user:1 name "subham"
hset user:1 role "admin"
hscan user:1 0 match "na*"
1) "0"
2) 1) "name"
2) "subham"
Sorted Set Operations with Redis
A sorted set data structure is a collection of unique elements sorted by a score. It is similar to a sorted list in other programming languages. Priority queues are often implemented using a sorted set data structure.
Sorted Set Operations
Here are some operations performed on a sorted set:
| Operation | Element | Score |
| Add | 1 | 1 |
| Add | 2 | 2 |
| Add | 3 | 3 |
| Remove | 3 | 3 |
| Remove | 2 | 2 |
| Remove | 1 | 1 |
Cli Commands
5.1.ZADD
This command adds the specified member to the sorted set with the specified score.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zrange user:1 0 -1 withscores
1) "subham"
2) "1"
3) "codexam"
4) "2"
5) "xamcodexam"
6) "3"
Visualize the sorted set in the Redis Commander.
| Index | Element | Score |
| 0 | subham | 1 |
| 1 | codexam | 2 |
| 2 | xamcodexam | 3 |
5.2.ZREM
This command removes the specified member from the sorted set.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zrem user:1 "subham"
zrange user:1 0 -1 withscores
1) "codexam"
2) "2"
3) "xamcodexam"
4) "3"
5.3.ZSCORE
This command returns the score of the specified member in the sorted set.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zscore user:1 "subham"
"1"
5.4.ZRANGE
This command returns the specified range of elements from the sorted set.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zrange user:1 0 -1 withscores
1) "subham"
2) "1"
3) "codexam"
4) "2"
5) "xamcodexam"
6) "3"
5.5.ZREVRANGE
This command returns the specified range of elements from the sorted set in reverse order.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zrevrange user:1 0 -1 withscores
1) "xamcodexam"
2) "3"
3) "codexam"
4) "2"
5) "subham"
6) "1"
5.6.ZRANGEBYSCORE
This command returns the specified range of elements from the sorted set by score.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zrangebyscore user:1 1 2 withscores
1) "subham"
2) "1"
3) "codexam"
4) "2"
5.7.ZREVRANGEBYSCORE
This command returns the specified range of elements from the sorted set by score in reverse order.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zrevrangebyscore user:1 2 1 withscores
1) "codexam"
2) "2"
3) "subham"
4) "1"
5.8.ZCARD
This command returns the number of elements in the sorted set.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zcard user:1
(integer) 3
5.9.ZCOUNT
This command returns the number of elements in the sorted set with a score between the specified minimum and maximum.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zcount user:1 1 2
(integer) 2
5.10.ZINCRBY
This command increments the score of the specified member in the sorted set by the specified value.
zadd user:1 1 "subham"
zincrby user:1 2 "subham"
zrange user:1 0 -1 withscores
1) "subham"
2) "3"
5.11.ZLEXCOUNT
This command returns the number of elements in the sorted set between the specified minimum and maximum.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zlexcount user:1 - +
(integer) 3
5.12.ZRANGEBYLEX
This command returns the specified range of elements from the sorted set by lexicographical order.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zrangebylex user:1 - +
1) "codexam"
2) "subham"
3) "xamcodexam"
5.13.ZREVRANGEBYLEX
This command returns the specified range of elements from the sorted set by lexicographical order in reverse order.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zrevrangebylex user:1 + -
1) "xamcodexam"
2) "subham"
3) "codexam"
5.14.ZREMRANGEBYLEX
This command removes the specified range of elements from the sorted set by lexicographical order.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zremrangebylex user:1 - +
(integer) 3
5.15.ZREMRANGEBYRANK
This command removes the specified range of elements from the sorted set by index.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zremrangebyrank user:1 0 1
(integer) 2
5.16.ZREMRANGEBYSCORE
This command removes the specified range of elements from the sorted set by score.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:1 3 "xamcodexam"
zremrangebyscore user:1 1 2
(integer) 2
This command removes the specified range of elements from the sorted set by score.
zadd score 1 "subham"
zadd score 2 "codexam"
zadd score 3 "xamcodexam"
zrange score 0 -2 withscores
1) "subham"
2) "1"
3) "codexam"
4) "2"
5.17.ZUNIONSTORE
This command stores the union of all the sorted sets specified.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:2 3 "xamcodexam"
zunionstore user:3 2 user:1 user:2
(integer) 3
zrange user:3 0 -1 withscores
1) "subham"
2) "1"
3) "codexam"
4) "2"
5) "xamcodexam"
6) "3"
5.18.ZINTERSTORE
This command stores the intersection of all the sorted sets specified.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:2 3 "xamcodexam"
zinterstore user:3 2 user:1 user:2
(integer) 1
zrange user:3 0 -1 withscores
1) "xamcodexam"
2) "3"
5.19.ZSCAN
This command scans the sorted set for members matching the specified pattern.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zadd user:2 3 "xamcodexam"
zscan user:1 0 match "sub*"
1) "0"
2) 1) "subham"
2) "1"
5.20.ZRANK
This command returns the rank of the specified member in the sorted set.
zadd user:1 1 "subham"
zadd user:1 2 "codexam"
zrank user:1 "subham"
(integer) 0
Note: Normally, sets are used to store unique elements. However, sorted sets allow you to store duplicate elements. This is because each element in a sorted set is associated with a score, which makes it unique and normal sets are unordered.
REDIS STREAMS OPERATIONS
Redis Streams is a new feature in Redis 5.0 that allows you to store multiple fields and values in a single key. It is similar to a log file in other programming languages. Redis Streams is often used to implement other data structures like queues and stacks.
Cli Commands
6.1.XADD
This command adds the specified fields and values to the stream.
It returns time stamp of the message.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xrange user:1 - +
1) 1) "1578060000000-0"
2) 1) "name"
2) "subham"
3) "role"
4) "admin"
2) 1) "1578060000001-0"
2) 1) "name"
2) "codexam"
3) "role"
4) "admin"
3) 1) "1578060000002-0"
2) 1) "name"
2) "xamcodexam"
3) "role"
4) "admin"
6.2.XLEN
This command returns the number of messages in the stream.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xlen user:1
(integer) 3
6.3.XRANGE
This command returns the specified range of messages from the stream.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xrange user:1 - +
1) 1) "1578060000000-0"
2) 1) "name"
2) "subham"
3) "role"
4) "admin"
2) 1) "1578060000001-0"
2) 1) "name"
2) "codexam"
3) "role"
4) "admin"
3) 1) "1578060000002-0"
2) 1) "name"
2) "xamcodexam"
3) "role"
4) "admin"
6.4.XREVRANGE
This command returns the specified range of messages from the stream in reverse order.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xrevrange user:1 + -
1) 1) "1578060000002-0"
2) 1) "name"
2) "xamcodexam"
3) "role"
4) "admin"
2) 1) "1578060000001-0"
2) 1) "name"
2) "codexam"
3) "role"
4) "admin"
3) 1) "1578060000000-0"
2) 1) "name"
2) "subham"
3) "role"
4) "admin"
6.5.XREAD
This command reads the specified number of messages from the stream.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xread count 2 streams user:1 0-0
1) 1) "user:1"
2) 1) 1) "1578060000000-0"
2) 1) "name"
2) "subham"
3) "role"
4) "admin"
2) 1) "1578060000001-0"
2) 1) "name"
2) "codexam"
3) "role"
4) "admin"
2) 1) "user:1"
2) 1) 1) "1578060000002-0"
2) 1) "name"
2) "xamcodexam"
3) "role"
4) "admin"
6.6.XREADGROUP
This command reads the specified number of messages from the stream in a consumer group.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xgroup create user:1 user:1 0-0 mkstream
xreadgroup group user:1 user:1 count 2 streams user:1 0-0
1) 1) "user:1"
2) 1) 1) "1578060000000-0"
2) 1) "name"
2) "subham"
3) "role"
4) "admin"
2) 1) "1578060000001-0"
2) 1) "name"
2) "codexam"
3) "role"
4) "admin"
2) 1) "user:1"
2) 1) 1) "1578060000002-0"
2) 1) "name"
2) "xamcodexam"
3) "role"
4) "admin"
6.7.XGROUP
This command creates a consumer group.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xgroup create user:1 user:1 0-0 mkstream
OK
6.8.XACK
This command acknowledges the specified messages in the stream.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xgroup create user:1 user:1 0-0 mkstream
xreadgroup group user:1 user:1 count 2 streams user:1 0-0
xack user:1 user:1 1578060000000-0 1578060000001-0
(integer) 2
6.9.XCLAIM
This command claims the specified messages in the stream.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xgroup create user:1 user:1 0-0 mkstream
xreadgroup group user:1 user:1 count 2 streams user:1 0-0
xclaim user:1 user:1 0-0 1578060000000-0 1578060000001-0
1) 1) "user:1"
2) 1) 1) "1578060000000-0"
2) 1) "name"
2) "subham"
3) "role"
4) "admin"
2) 1) "1578060000001-0"
2) 1) "name"
2) "codexam"
3) "role"
4) "admin"
2) 1) "user:1"
2) 1) 1) "1578060000002-0"
2) 1) "name"
2) "xamcodexam"
3) "role"
4) "admin"
6.10.XDEL
This command deletes the specified messages in the stream.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xgroup create user:1 user:1 0-0 mkstream
xreadgroup group user:1 user:1 count 2 streams user:1 0-0
xdel user:1 1578060000000-0 1578060000001-0
(integer) 2
6.11.XTRIM
This command trims the specified messages in the stream.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xtrim user:1 maxlen 2
(integer) 1
6.12.XINFO
This command returns information about the stream.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xinfo stream user:1
1) 1) "length"
2) (integer) 2
2) 1) "radix-tree-keys"
2) (integer) 1
3) 1) "radix-tree-nodes"
2) (integer) 2
4) 1) "groups"
2) (integer) 1
5) 1) "last-generated-id"
2) "1578060000001-0"
6) 1) "first-entry"
2) 1) "1578060000000-0"
2) 1) "name"
2) "subham"
3) "role"
4) "admin"
7) 1) "last-entry"
2) 1) "1578060000001-0"
2) 1) "name"
2) "codexam"
3) "role"
4) "admin"
6.13.XSETID
This command sets the id of the stream.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xgroup create user:1 user:1 0-0 mkstream
xreadgroup group user:1 user:1 count 2 streams user:1 0-0
xsetid user:1 1578060000000-0
OK
6.14.XREWRITE
This command rewrites the stream to optimize memory usage.
xadd user:1 * name "subham" role "admin"
xadd user:1 * name "codexam" role "admin"
xadd user:1 * name "xamcodexam" role "admin"
xgroup create user:1 user:1 0-0 mkstream
xreadgroup group user:1 user:1 count 2 streams user:1 0-0
xrewrite user:1
(integer) 1
Redis Bitmaps
A bitmap data structure is a collection of bits. It is similar to an array in other programming languages. Bitmaps are often used to implement other data structures like sets and bloom filters.
Cli Commands
7.1.SETBIT
This command sets the bit at the specified index in the bitmap to either 1 or 0.
SETBIT pings:2024-01-01-00:00 123 1
(integer) 0
SETBIT pings:2024-01-01-00:00 456 1
(integer) 0
7.2.GETBIT
This command returns the value of the bit at the specified index in the bitmap.
SETBIT pings:2024-01-01-00:00 123 1
(integer) 0
GETBIT pings:2024-01-01-00:00 123
(integer) 1
7.3.BITCOUNT
This command returns the number of bits set to 1 in the bitmap.
SETBIT pings:2024-01-01-00:00 123 1
(integer) 0
SETBIT pings:2024-01-01-00:00 456 1
(integer) 0
BITCOUNT pings:2024-01-01-00:00
(integer) 2
7.4.BITOP
This command performs a bitwise operation between the bitmaps and stores the result in the destination bitmap.
SETBIT pings:2024-01-01-00:00 123 1
(integer) 0
SETBIT pings:2024-01-01-00:00 456 1
(integer) 0
BITOP AND pings:2024-01-01-00:00 pings:2024-01-01-00:00 pings:2024-01-01-00:00
(integer) 2
7.5.BITPOS
This command returns the index of the first bit set to 1 or 0 in the bitmap.
SETBIT pings:2024-01-01-00:00 123 1
(integer) 0
BITPOS pings:2024-01-01-00:00 1
(integer) 123
7.6.BITFIELD
This command performs a bitwise operation between the bitmaps and stores the result in the destination bitmap.
BITFIELD pings:2024-01-01-00:00 INCRBY i5 100 1 GET u4 0
1) (integer) 0
2) (integer) 0
3) (integer) 0
4) (integer) 0
.....
Geospatial Operations
A geospatial data structure is a collection of elements with a geospatial location. It is similar to a map in other programming languages. Geospatial data structures are often used to implement other data structures like geohashes and geofences.
Cli Commands
8.1.GEOADD
This command adds the specified elements to the geospatial data structure.
geoadd user:1 88.3639 22.5726 "subham"
(integer) 1
geoadd user:1 88.3639 22.5726 "codexam"
(integer) 1
8.2.GEOPOS
This command returns the longitude and latitude of the specified elements in the geospatial data structure.
geoadd user:1 88.3639 22.5726 "subham"
(integer) 1
geoadd user:1 88.3639 22.5726 "codexam"
(integer) 1
geopos user:1 "subham" "codexam"
1) 1) "88.36389994668960571"
2) "22.57260005994199279"
2) 1) "88.36389994668960571"
2) "22.57260005994199279"
8.3.GEODIST
This command returns the distance between the specified elements in the geospatial data structure.
geoadd user:1 88.3639 22.5726 "subham"
(integer) 1
geoadd user:1 88.3639 22.5726 "codexam"
(integer) 1
geodist user:1 "subham" "codexam" km
"0.0000"
8.4.GEORADIUS
This command returns the elements within the specified radius in the geospatial data structure.
geoadd user:1 88.3639 22.5726 "subham"
(integer) 1
geoadd user:1 88.3639 22.5726 "codexam"
(integer) 1
georadius user:1 88.3639 22.5726 100 km
1) "subham"
2) "codexam"
8.5.GEORADIUSBYMEMBER
This command returns the elements within the specified radius in the geospatial data structure.
geoadd user:1 88.3639 22.5726 "subham"
(integer) 1
geoadd user:1 88.3639 22.5726 "codexam"
(integer) 1
georadiusbymember user:1 "subham" 100 km
1) "subham"
2) "codexam"
8.6.GEOHASH
This command returns the geohash of the specified elements in the geospatial data structure.
geoadd user:1 88.3639 22.5726 "subham"
(integer) 1
geoadd user:1 88.3639 22.5726 "codexam"
(integer) 1
geohash user:1 "subham" "codexam"
1) "tqg0y0y0y0y0"
2) "tqg0y0y0y0y0"
8.7.GEOSEARCH
This command returns the elements matching the specified query in the geospatial data structure.
geoadd user:1 88.3639 22.5726 "subham"
(integer) 1
geoadd user:1 88.3639 22.5726 "codexam"
(integer) 1
geosearch user:1 frommember "subham" count 2
1) 1) "subham"
2) 1) "88.36389994668960571"
2) "22.57260005994199279"
2) 1) "codexam"
2) 1) "88.36389994668960571"
2) "22.57260005994199279"
8.8.GEOSEARCHSTORE
This command stores the elements matching the specified query in the geospatial data structure.
geoadd user:1 88.3639 22.5726 "subham"
(integer) 1
geoadd user:1 88.3639 22.5726 "codexam"
(integer) 1
geosearchstore user:2 frommember "subham" count 2
(integer) 2
Probabilistic Data Structures
You can use probabilistic data structures to store elements with a probability of false positives. It is similar to a set in other programming languages. Probabilistic data structures are often used to implement other data structures like bloom filters.
READ HERE: https://redis.io/docs/data-types/probabilistic/t-digest/
Time Series Data Structures
A time series data structure is a collection of elements with a timestamp. It is similar to a map in other programming languages. Time series data structures are often used to implement other data structures like time series.
READ HERE: https://redis.io/docs/data-types/timeseries/
Pub/Sub
Redis Pub/Sub implements the messaging system where the senders (publishers) sends the messages while the receivers (subscribers) receive them. The link between the publishers and subscribers is called channel.
Step 1: Open two terminals.
Open redis-cli in the first terminal and also in the second terminal. (steps are the given below)
docker ps (to get the container id)
if not running then run the container using docker start container_id or
docker start redis-stackand thendocker exec -it redis-stack redis-cliordocker exec -it container_id bashand thenredis-clito open redis-cli.
Now write the following command in the first terminal to subscribe to the channel.
SUBSCRIBE notifications
- Now write the following command in the second terminal to publish a message to the channel.
PUBLISH notifications "Hello, World!"
- You will see the following output in the first terminal.
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "notification"
3) (integer) 1
1) "message"
2) "notification"
3) "subham"
Reading messages... (press Ctrl-C to quit)
It is beneficial when you want to scale your socket.io application. You can use redis pub/sub to communicate between multiple socket.io servers.
Some Usecases of Redis Pub/Sub
Chat application
Real-time analytics
Real-time notifications
Distributed locks
Distributed cache invalidation
Distributed session management
Distributed job queue
Distributed event-driven programming
Distributed publish/subscribe system
Distributed system monitoring
Distributed system coordination
Distributed system configuration
Cli Commands
9.1.SUBSCRIBE
This command subscribes to the specified channels.
SUBSCRIBE notifications
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "notifications"
3) (integer) 1
9.2.UNSUBSCRIBE
This command unsubscribes from the specified channels.
SUBSCRIBE notifications
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "notifications"
3) (integer) 1
UNSUBSCRIBE notifications
Reading messages... (press Ctrl-C to quit)
1) "unsubscribe"
2) "notifications"
3) (integer) 0
9.3.PUBLISH
This command publishes the specified message to the specified channel.
SUBSCRIBE notifications
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "notifications"
3) (integer) 1
PUBLISH notifications "Hello, World!"
(integer) 1
1) "message"
2) "notifications"
3) "Hello, World!"
9.4.PUBSUB
This command returns information about the channels.
SUBSCRIBE notifications
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "notifications"
3) (integer) 1
PUBSUB CHANNELS
1) "notifications"
There are a lot of other commands in redis-cli. You can check them out by typing help in redis-cli.
Scale A Node.js Application With Redis
- Step 1. Initialize a Node.js project.
Copy the template what I already created for you.
npm ireplace the .env file with your own database credentials.
npm startto run the project.
- Third party api: https://jsonplaceholder.typicode.com/todos
We will try to speed up the api response time using redis.
npm i axiosto install axios.
- Open server/src folder makes a new file todos.ts
import express from "express";
import axios from "axios";
const todos = express.Router();
todos.get("/todos", async (req, res) => {
try {
const { data } = await axios.get("https://jsonplaceholder.typicode.com/todos");
res.json(data);
} catch (error:any) {
console.error("Error fetching todos:", error.message);
res.status(500).json({ error: "Internal Server Error" });
}
});
export default todos;
- Open server/src/app.ts and add the route to the express app.
app.use("/api/v1/", todos);
now run
npm run devand go to http://localhost:5050/api/v1/todos to see the response.I have already setup Morgan for logging for response times, however, you can open Postman and check the response times.
In the first fetching it takes 403ms to fetch the data from the api, and after multiple requests, it takes 120ms–351ms to fetch the data from the api.
Now try to implement caching using redis.
- you can find the client.ts file in the server/src folder.
import Redis from "ioredis";
const client = new Redis(
{
host: 'localhost', // replace with your host, if not localhost
port: 6379 // replace with your port, if not 6379
}
);
export default client;
- Now open server/src/todos.ts and import the redis client.
import client from "./client";
todos.get("/todos", async (req, res) => {
try {
const todos = await client.get("todos");
if (todos) {
console.log("Fetching from redis");
return res.json(JSON.parse(todos));
}
const { data } = await axios.get("https://jsonplaceholder.typicode.com/todos");
client.set("todos", JSON.stringify(data));
console.log("Fetching from api");
res.json(data);
} catch (error:any) {
console.error("Error fetching todos:", error.message);
res.status(500).json({ error: "Internal Server Error" });
}
});
Now run
npm run devand go to http://localhost:5050/api/v1/todos to see the response.In the first fetching it takes 403ms to fetch the data from the api, and after multiple requests, it takes 0ms–1ms to fetch the data from the redis.
you can also add
client.set("todos", JSON.stringify(data), "EX", 10)to set the expiration time of the key.Now open you redis-cli and run
keys *to see the keys andttl todosto see the expiration time of the key.If you open redis-stack container, you can see the todos with data.
Now you can scale your application by adding multiple instances of the application and using redis to cache the data.
Thank you for reading this blog and stay tuned for more. If you have any questions or feedback, feel free to leave a comment below or contact me directly. I would love to hear from you. 🙌
If you are looking for a freelance web developer who can help you with your projects, you can also contact me. I can help you build fast, scalable, and user-friendly web applications. 💯
I look forward to hearing from you and collaborating with you on your projects. 🙌
Until next time, happy coding! 👋