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

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

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

<dependency>
    <groupId>com.ohmdb</groupId>
    <artifactId>ohmdb-all</artifactId>
    <version>1.0.0</version>
</dependency>

• Add the ohmdb-all 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();
	}
}

• 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!"

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