Range lock tx.createReadStream()

[cshum]

Range lock tx.createReadStream() is an essential but non-trivial feature to implement.

Things to consider:

• Need to snapshot the whole readStream range.
• Level of locking: global, prefix or ltgt based?

[delaneyj]

I would like this as well, my guess is ltgt based would give the most options.

[cshum]

Instead of range lock, createReadStream now performs implicit snapshot same as Leveldown, with isolated result set.