OhmDB

OhmDB is "the irresistible database" that offers the power of relational databases and the flexibility of NoSQL databases.

Fork

OhmDB is a great tool to persist, retrieve, and query objects from disk. Whether it lives up to the above blockquote written by the original author is for you to decide.

This fork of OhmDB makes some modest changes including...

Requiring Java 8
Improved support for nested POJO fields persisted in your tables
Ensures strings are encoded and decoded as UTF8 instead of the system encoding.

While the API remains unchanged, the change to the string encoding may not be compatible with existing OhmDB 1.0.0 files. YMMV.

Apache Public License v2

OhmDB is released under the liberal APL v2 license, so it is free to use for both commercial and non-commercial projects.

Using with Maven

Add the following snippet to the <dependencies> section in pom.xml:

<dependency>
    <groupId>com.gitblit.ohmdb</groupId>
    <artifactId>ohmdb</artifactId>
    <version>1.0.2</version>
</dependency>

Quick start

Add the ohmdb dependency to your Maven project (as described above).
Add the following code to your project, and execute it:

import com.ohmdb.api.*;

class Person { public String name; public int age; }

public class Main {
	public static void main(String[] args) {
		Db db = Ohm.db("ohm.db");
		Table<Person> persons = db.table(Person.class);
		Person $p = persons.queryHelper();

		Person p1 = new Person();
		p1.name = "Niko";
		p1.age = 30;
		long id = persons.insert(p1);
		Person p2 = persons.get(id);

		persons.createIndexOn($p.age);
		Person[] adults = persons.where($p.age).gte(18).get();
      
        db.shutdown();
	}
}

Features

Simple setup, no configuration (just add it as Maven dependency, and you are ready!)
Delightful API:

Ohm.db("ohm.db").table(Item.class).insert(new Item("item1"));

or just:

DB.insert(new Item("item1"));

ACID transactions with automatic recovery
Fast joins through graph-based relations with graph traversal optimization
Automatic schema migration
Single-file storage (e.g. my.db), so "backup" == "copy the file!"

Contributing

Fork (and then git clone https://github.com/gitblit/ohmdb.git).
Create a branch (git checkout -b branch_name).
Commit your changes (git commit -am "Description of contribution").
Push to the branch (git push origin branch_name).
Open a Pull Request.
Thank you for your contribution! Wait for a response...

gitblit / ohmdb