Max databases count

What is the highest possible number of the Redis database index?
What would be a reasonable number?
I am aware of the fact that Redis doesn’t use the database index for performance optimization.
I use it - additionally with salting the cache keys - to better isolate the different keys for different applications.

Would 128 be a sane database max count?

Database indexes aren’t really recommended because clustering doesn’t support them. 128 is fine, as long as you have enough memory to hold your dataset.