MapDB combines embedded database engine and Java collections. It is free under Apache 2 license. MapDB is flexible and can be used in many roles:
- Drop-in replacement for Maps, Lists, Queues and other collections.
- Off-heap collections not affected by Garbage Collector
- Multilevel cache with expiration and disk overflow.
- RDBMs replacement with transactions, MVCC, incremental backups etc…
- Local data processing and filtering. MapDB has utilities to process huge quantities of data in reasonable time.
Maven snippet, VERSION is
<dependency>
<groupId>org.mapdb</groupId>
<artifactId>mapdb</artifactId>
<version>VERSION</version>
</dependency>
Hello world:
//import org.mapdb.*
DB db = DBMaker.memoryDB().make();
ConcurrentMap map = db.hashMap("map").make();
map.put("something", "here");
Continue at Quick Start or at Documentation.
More details.
MapDB is written in Kotlin. You will need Intellij Idea 15 Community Edition to edit it.
Use Maven to build MapDB: mvn install
You might experience problem with mapdb-jcache-tck-test module.
It expects mapdb-jcache module to be already installed in local maven repo.
Source code module dependency does not work. To run all tests use command: mvn install test
MapDB comes with extensive unit tests, by default only tiny fraction is executed, so build finishes under 10 minutes.
Full test suite has over million test cases and runs several hours/days.
To run full test suite set -Dmdbtest=1 property.
It is recommended to run tests in parallel: -DthreadCount=16.
It is also possible to override temporary folder with -Djava.io.tmpdir=/path directive.
An example to run full acceptance tests:
mvn clean install test -Dmdbtest=1 -DthreadCount=16 -Djava.io.tmpdir=/mnt/big