HeliDB

About

Welcome to the home page of HeliDB – a simple and fast Java database!

HeliDB is a database for persisting key—value pairs from a Java program. Users have many choices in configuring what capabilities they want the database to have and in how the data is stored. In its simplest configuration, HeliDB is just a file-backed Map. More advanced configurations support transactions and fast searches and inserts through using B+ Trees.

Notable features are:

The HeliDB Database interface extends Java's Map, so a HeliDB database can be used as a drop-in replacement for a Map.
The Database interface defines methods that are more efficient for working with persistent data than the methods from Map.
A database can be configured to support transactions.
Database operations can be made faster by indexing data in B+ Trees.
Database object creation is fast, so clients can create new databases as necessary without having to worry about performance.
The database runs in the same process as the Java program which makes database calls just local function calls. (i.e. fast)

When should I use HeliDB?

HeliDB is a great choice when you want to persist key—value pairs, but don't want to use a full-blown SQL database.

What limitations does HeliDB have?

Data is stored as key—value pairs. There is no way of searching for data within values (like selecting for data in table columns in an SQL database).
Transactions don't allow concurrent writes to the same database.

News

09/21/2009: HeliDB 1.1.1 released: Version 1.1.1 comes with performance improvements for the BPlusTree and the ConstantSizeStringSerializer. See the release notes and the change log for details.
07/26/2009: HeliDB 1.1 released: This release adds support for searching for closest key matches. The new Cursor can be used to navigate through the records in a database. See the release notes and the change log for details.
07/15/2009: HeliDB 1.0.2 released: This version updates the EntityFS dependency to version 1.1.3. See the release notes and the change log for details.
02/06/2009: HeliDB 1.0.1 released: This version upgrades the EntityFS dependency to version 1.1. See the release notes and the change log for details.
08/27/2008: HeliDB 1.0 released: The initial version of HeliDB was released.