Max key length is hardcoded to `Byte.MAX_VALUE` (127) about halodb

[scottcarey]

It just throws an exception and breaks if you go over 127, I don't see any reason in the code other than inefficiency (keys are written to disk twice and must be resident in memory) that the limit exists.

I suppose at that size you could substitute a ~ 16 to 24 byte hash of the key instead. If all you need is lookup, a long enough hash should be fine. But I have run into this limit in cases where I also need to iterate over key/value pairs, and needed another indirection (map from hash to real key in another db, allowing slow scans and wasting memory). This was too slow so I went back to another storage engine for that use case.

[wangtao724]

Mark this as duplicate to #42