ConstructCompositeHistoryKey builds the History Key of namespace~key~blocknum~trannum using an order preserving encoding so that history query results are ordered by height.

ConstructPartialCompositeHistoryKey builds a partial History Key namespace~key~ for use in history key range queries.

SplitCompositeHistoryKey splits the key bytes using a separator.

CompositeKeySep is a nil byte used as a separator between different components of a composite key.

HistoryDB - an interface that a history database should implement.

HistoryDBProvider provides an instance of a history DB.