flushdb not clear all keys in redis?

Question

It seems there are still some keys left after i ran redis SHELL command flushdb,

what are these keys used for and why flushdb does not work?

Answer 1

When Redis runs flushdb command, it blocks any new writings to the database, and flushes all keys in the database. However, when Redis finishes the flushdb command, it can receive new writings, i.e. other Redis client can put new keys into the database.

In your case, I think there're other clients constantly writing to the database. So after you flush the database, new keys are put into Redis by other clients.

If you want to stop any further writing, you have to shutdown Redis server.