EliasDB

EliasDB is a graph based database which aims to provide a lightweight solution for projects which want to store their data as a graph. EliasDB does not require any third-party libraries.

Features

• Build on top of a fast key-value store which supports transactions and memory-only storage.
• Data is stored in nodes (key-value objects) which are connected via edges.
• Stored graphs can be separated via partitions.
• Stored graphs support cascading deletions - delete one node and all its "children".
• All stored data is indexed and can be quickly searched via a full text phrase search.
• For more complex queries EliasDB has an own query language called EQL with an sql-like syntax.
• Written in Go from scratch. No third party libraries were used apart from Go's standard library.
• The database can be embedded or used as a standalone application.
• When used as a standalone application it comes with an internal HTTPS webserver which provides a REST API and a basic file server.
• When used as an embedded database it supports transactions with rollbacks, iteration of data and rule based consistency management.

Getting Started (standalone application)

You can download a precompiled package for Windows (win64) or Linux (amd64) here.

Extract it and execute the executable. The executable should automatically create 3 subfolders and a configuration file. It should start an HTTPS server on port 9090. To see a terminal point your webbrowser to:

https://localhost:9090/db/term.html

After accepting the self-signed certificate from the server you should see a web terminal. EliasDB can be stopped with a simple CTRL+C or by overwriting the content in eliasdb.lck with a single character.

Tutorial:

To get an idea of what EliasDB is about have a look at the tutorial.

REST API:

The terminal uses a REST API to communicate with the backend. The REST API can be browsed using a dynamically generated swagger.json definition (https://localhost:9090/db/swagger.json). You can browse the API of EliasDB's latest version here.

Command line options

EliasDB has a few command line options. Using these runs the main executable like a normal command line tool:

Usage of  ./eliasdb  [options]
  -?	Show this help message
  -dumpdb string
    	Dump the contents of a partition to a JSON file and exit
  -import string
    	Import a graph from a JSON file to a partition (exit if storing on disk)
  -part string
    	Partition to operate on when importing or dumping data

Configuration

EliasDB uses a single configuration file called eliasdb.config.json. After starting EliasDB for the first time it should create a default configuration file. Available configurations are:

Configuration Option	Description
EnableReadOnly	Flag if the datastore should be open read-only.
EnableWebFolder	Flag if the files in the webfolder /web should be served up by the webserver. If false only the REST API is accessible.
EnableWebTerminal	Flag if the web terminal file /web/db/term.html should be created.
HTTPSCertificate	Name of the webserver certificate which should be used. A new one is created if it does not exist.
HTTPSHost	Hostname the webserver should listen to. This host is also used in the dynamically generated swagger definition.
HTTPSKey	Name of the webserver private key which should be used. A new one is created if it does not exist.
HTTPSPort	Port on which the webserver should listen on.
LocationDatastore	Directory for datastore files.
LocationHTTPS	Directory for the webserver's SSL related files.
LocationWebFolder	Directory of the webserver's webfolder.
LockFile	Lockfile for the webserver which will be watched duing runtime. Replacing the content of this file with a single character will shutdown the webserver gracefully.
MemoryOnlyStorage	Flag if the datastore should only be kept in memory.
ResultCacheMaxAgeSeconds	EQL queries create result sets which are cached. The value describes the amount of time in seconds a result is kept in the cache.
ResultCacheMaxSize	EQL queries create result sets which are cached. The value describes the number of results which can be kept in the cache.

Note: It is not (and will never be) possible to access the REST API via HTTP.

Building EliasDB

To build EliasDB from source you need to have Go installed. There a are two options:

Checkout from github (use this method if you want code + documentation and tutorials):

Create a directory, change into it and run:

git clone https://github.com/krotik/eliasdb/ .

Assuming your GOPATH is set to the new directory you should be able to build the binary with:

go install devt.de/eliasdb

Using go get (use this method if you want to embed EliasDB in your project):

Create a directory, change into it and run:

go get -d devt.de/common devt.de/eliasdb

Assuming your GOPATH is set to the new directory you should be able to build the binary with:

go build devt.de/eliasdb

Further Reading

• A design document which describes the different components of the graph database. Link
• A reference for the EliasDB query language EQL. Link
• A quick overview of what you can do when you embed EliasDB in your own Go project. Link

License

EliasDB source code is available under the Mozilla Public License.