Leveldb is a fast key-value storage library written at google that provides an ordered mapping from string keys to string values.

features:
* keys and values are arbitrary byte arrays.
* data is stored sorted by key.
* callers can provide a custom comparison function to override
the sort order.
* the basic operations are put(key,value), get(key), delete(key).
* multiple changes can be made in one atomic batch.
* users can create a transient snapshot to get a consistent view of
data.
* forward and backward iteration is supported over the data.
* data is automatically compressed using the snappy compression
library.
* external activity (file system operations etc.) is relayed through
a virtual interface so users can customize the operating system
interactions.
* detailed documentation about how to use the library is included with
the source code.
limitations:
* this is not a sql database. it does not have a relational data model,
it does not support sql queries, and it has no support for indexes.
* only a single process (possibly multi-threaded) can access a
particular database at a time.
* there is no client-server support builtin to the library.
an application that needs such support will have to wrap their own
server around the library.
this package provides the shared library.