How would you get the last 10 keys redis?

Question

Let's say I have a database with 1,000,000 keys. Is there a way to know the last 10 keys from that database?

Victoir

nope, you have to implement it yourself – Sheppard

And how would you go about doing this? – Victoir

you can store keys in a list or in a sorted set – Sheppard

I see. So I would need make a list that stores all the available keys? – Victoir

well depending on the space you want to invest with this.I would keep the size of this list to a fixed length – Sheppard

Would there be a way to even get the last key in the database? – Victoir

@Sivapriyan can you tell us more about what you need the last 10 keys in particular for? Maybe we can recommend a workaround. As Tommaso Barbugli said, to do what you want, you'd need to use a secondary structure like a list or a sorted set (slower) to get at the last n keys. – Uprising

what is "last" in "the last 10 keys"? – Hamster

Answer 1

You will need to maintain it as another list using the following commands.

Add new key to the front of the list  
LPUSH last10keys key

Retain only the last 10
LTRIM last10keys 0 9

Get the last keys - will return 10 or less
LRANGE mylist 0 9 

Kutaisi

Answer 2

As a workaround if I don't want to change anything in the cache, I tail the AOF file to see what's the latest change there.

tail -f /var/lib/redis/appendonly.aof

From there, you can see the key, value and command used.

Famulus

This requires appendonly to be set to yes in the config file. That is not the default. – Dissipation

Answer 3

You can use pipeline to get last inserted keys or specific keys from the Redis Database

Here is my code example :

r = redis.StrictRedis(host='localhost', port= 6379, db =0)
# Day1 hash for 24 hours 
# Key , Field , Value
r.hset("31/8/21", "12am", "/home/user/video1.mp4")
r.hset("31/8/21", "1am", "/home/user/video2.mp4")
r.hset("31/8/21", "2am", "/home/user/video3.mp4")
r.hset("31/8/21", "3am", "/home/user/video4.mp4")
r.hset("31/8/21", "4am", "/home/user/video5.mp4")
.
.
#Created sorted set for all the date hashes into single "date" key
r.sadd("date", "25/8/21")
r.sadd("date", "26/8/21")
r.sadd("date", "27/8/21")
r.sadd("date", "28/8/21")
r.sadd("date", "29/8/21")
r.sadd("date", "30/8/21")
r.sadd("date", "31/8/21")
r.save

@app.get("/lastweek")
def sortweek():
        lastweeklist = r.sort("date", 27, -1, alpha=True) #sorted set key > date
        pipe = r.pipeline()
        for keys in lastweeklist:
                pipe.hgetall(keys) #hvals
        week1 = []
        for week in pipe.execute():
                week1.append(week)
        return week1

Antecedency

Answer 4

Some commands has [LIMIT offset count] wich you can fill and get limited number of items.

like zrevrangebyscore key +inf 0 LIMIT 0 20 which gives you top 20 items of a sorted set.

Handle