levedb是否支持仅键迭代？

Question

I'm using goleveldb which is an implementation of leveldb in Go and I need to iterate over keys with a prefix. It supports prefix-iteration but when iterating over keys, it seems that the values are also fetched under the hood. This leads to a huge performance drawback when dealing with a big database. From the documentations and code I didn't find a way to iterate over keys without fetching values neither in Go implementation nor in original C++ implementation. If there is a way to do so, I would appreciate someone helping me to get in the right direction.