Table of Contents API documentation

Druid extensions

Druid implements an extension system that allows for adding functionality at runtime. Extensions are commonly used to add support for deep storages (like HDFS and S3), metadata stores (like MySQL and PostgreSQL), new aggregators, new input formats, and so on.

Production clusters will generally use at least two extensions; one for deep storage and one for a metadata store. Many clusters will also use additional extensions.

Including extensions

Please see here.

Core extensions

Core extensions are maintained by Druid committers.

Name Description Docs
druid-avro-extensions Support for data in Apache Avro data format. link
druid-caffeine-cache A local cache implementation backed by Caffeine. link
druid-datasketches Support for approximate counts and set operations with DataSketches. link
druid-hdfs-storage HDFS deep storage. link
druid-histogram Approximate histograms and quantiles aggregator. link
druid-kafka-eight Kafka ingest firehose (high level consumer) for realtime nodes. link
druid-kafka-extraction-namespace Kafka-based namespaced lookup. Requires namespace lookup extension. link
druid-kafka-indexing-service Supervised exactly-once Kafka ingestion for the indexing service. link
druid-lookups-cached-global A module for lookups providing a jvm-global eager caching for lookups. It provides JDBC and URI implementations for fetching lookup data. link
druid-lookups-cached-single Per lookup caching module to support the use cases where a lookup need to be isolated from the global pool of lookups link
druid-s3-extensions Interfacing with data in AWS S3, and using S3 as deep storage. link
druid-stats Statistics related module including variance and standard deviation. link
mysql-metadata-storage MySQL metadata store. link
postgresql-metadata-storage PostgreSQL metadata store. link

Community Extensions

Community extensions are not maintained by Druid committers, although we accept patches from community members using these extensions. They may not have been as extensively tested as the core extensions.

A number of community members have contributed their own extensions to Druid that are not packaged with the default Druid tarball.
If you'd like to take on maintenance for a community extension, please post on druid-development group to let us know!

All of these community extensions can be downloaded using pull-deps with the coordinate io.druid.extensions.contrib:EXTENSION_NAME:LATEST_DRUID_STABLE_VERSION.

Name Description Docs
druid-azure-extensions Microsoft Azure deep storage. link
druid-cassandra-storage Apache Cassandra deep storage. link
druid-cloudfiles-extensions Rackspace Cloudfiles deep storage and firehose. link
druid-distinctcount DistinctCount aggregator link
druid-kafka-eight-simpleConsumer Kafka ingest firehose (low level consumer). link
druid-orc-extensions Support for data in Apache Orc data format. link
druid-parquet-extensions Support for data in Apache Parquet data format. Requires druid-avro-extensions to be loaded. link
druid-rabbitmq RabbitMQ firehose. link
druid-rocketmq RocketMQ firehose. link
graphite-emitter Graphite metrics emitter link
statsd-emitter StatsD metrics emitter link

Promoting Community Extension to Core Extension

Please let us know if you'd like an extension to be promoted to core. If we see a community extension actively supported by the community, we can promote it to core based on community feedback.

Creating your own Extensions

For information how to create your own extension, please see here.