FromVlog produces an index from the data in the value log.

ReadTrailer reads the trailer of the index log.

WriteIndex is a convenience function to write the contents of `idx` to `path`.

LocationSize is the physical storage of a single item (8 for the key, 8 for the wal offset, 4 for the len).

Index is an in-memory representation of the batch index as b-tree structure.

Reader gives access to a single index on disk.