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?

Solution 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 

Solution 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.

Comments

[Tommaso Barbugli]

nope, you have to implement it yourself

[Siva]

And how would you go about doing this?

[Tommaso Barbugli]

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

[Siva]

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

[Tommaso Barbugli]

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

[Siva]

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

[Eli]

@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.

[akonsu]

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

[Zitrax]

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