Time Series. But also prefix lookup. You can do some sweet tricks with trees where lookup on strings can use a prefix and then you get an iterator. You can the

Time Series. But also prefix lookup. You can do some sweet tricks with trees where lookup on strings can use a prefix and then you get an iterator. You can then use this iterator to read the items until you find one where the prefix doesn't match. I've used this in developing storage systems, but it seems like a useful trick that I might want to use elsewhere.