is there any significant cost in using snapshot for a long time

[Ren Z]

Suppose I've made a snapshot and iterate through all the keys using it (to make a copy of a db). If db is large and under heavy read/write while doing this, is there any significant cost in terms of anything for holding snapshot for a long time?

[Robert Escriva]

Holding the snapshot will delay garbage collection of all data within
the snapshot, and all data overwritten after the snapshot is taken. So
if you frequently rewrite keys, you'll (potentially) end up with much
more disk usage than you would see in steady state without the snapshot.

-Robert