leveldb – A fast and lightweight key/value database library by Google

leveldb – A fast and lightweight key/value database library by Google

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.

Performance

Here is a performance report (with explanations) from the run of the included db_bench program. The results are somewhat noisy, but should be enough to get a ballpark performance estimate.

 

This entry was posted in Uncategorized. Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s