# mapdb

**Repository Path**: mirrors/mapdb

## Basic Information

- **Project Name**: mapdb
- **Description**: MapDB是一个快速、易用的嵌入式Java数据库引擎，它提供了基于磁盘或者堆外（off-heap允许Java直接操作内存空间, 类似于C的malloc和free）存储的并发的Map
- **Primary Language**: Java
- **License**: Apache-2.0
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 24
- **Forks**: 0
- **Created**: 2017-07-17
- **Last Updated**: 2024-03-02

## Categories & Tags

**Categories**: database-service

**Tags**: None

## README

<img src="https://raw.githubusercontent.com/jankotek/mapdb-site/gh-pages/images/art/rocket-small.png" width=90 height=90 align="left"/>

MapDB: database engine 
=======================
[![Build Status](https://travis-ci.org/jankotek/mapdb.svg?branch=master)](https://travis-ci.org/jankotek/mapdb)
[![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.mapdb/mapdb/badge.svg)](https://search.maven.org/#search%7Cga%7C1%7Cg%3A%22org.mapdb%22%20AND%20a%3Amapdb)
[![Join the chat at https://gitter.im/jankotek/mapdb](https://badges.gitter.im/jankotek/mapdb.svg)](https://gitter.im/jankotek/mapdb?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)


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.

Hello world
-------------------

Maven snippet, VERSION is [![Maven Central](https://maven-badges.herokuapp.com/maven-central/org.mapdb/mapdb/badge.svg)](https://search.maven.org/#search%7Cga%7C1%7Cg%3A%22org.mapdb%22%20AND%20a%3Amapdb)

```xml
<dependency>
    <groupId>org.mapdb</groupId>
    <artifactId>mapdb</artifactId>
    <version>VERSION</version>
</dependency>
```

Hello world:

```java
//import org.mapdb.*
DB db = DBMaker.memoryDB().make();
ConcurrentMap map = db.hashMap("map").make();
map.put("something", "here");
```

You can continue with [quick start](https://jankotek.gitbooks.io/mapdb/content/quick-start/) or refer to the  [documentation](https://jankotek.gitbooks.io/mapdb/).

Support
------------

More [details](http://www.mapdb.org/support/).

Development
--------------------

MapDB is written in Kotlin, you will need IntelliJ Idea.

You can use Gradle to build MapDB.

MapDB is extensively unit-tested.
By default, only tiny fraction of all tests are executed, so build finishes under 10 minutes.
Full test suite has over million test cases and runs for several hours/days.
To run full test suite, set `-Dmdbtest=1` VM option.

Longer unit tests might require more memory. Use this to increase heap memory assigned to unit tests: `-DtestArgLine="-Xmx3G"`

By default unit tests are executed in 3 threads. Thread count is controlled by `-DtestThreadCount=3` property

On machine with limited memory you can change fork mode so unit test consume less RAM, but run longer: `-DtestReuseForks=false`