<!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>Extensions · Apache Druid</title><meta name="viewport" content="width=device-width"/><link rel="canonical" href="https://druid.apache.org/docs/0.16.1-incubating/development/extensions.html"/><meta name="generator" content="Docusaurus"/><meta name="description" content="&lt;!--"/><meta name="docsearch:language" content="en"/><meta name="docsearch:version" content="0.16.1-incubating" /><meta property="og:title" content="Extensions · Apache Druid"/><meta property="og:type" content="website"/><meta property="og:url" content="https://druid.apache.org/index.html"/><meta property="og:description" content="&lt;!--"/><meta property="og:image" content="https://druid.apache.org/img/druid_nav.png"/><meta name="twitter:card" content="summary"/><meta name="twitter:image" content="https://druid.apache.org/img/druid_nav.png"/><link rel="shortcut icon" href="/img/favicon.png"/><link rel="stylesheet" href="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.css"/><link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/styles/default.min.css"/><script async="" src="https://www.googletagmanager.com/gtag/js?id=UA-131010415-1"></script><script>
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class="icon-toc"></i></div></div><div class="navGroups"><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Getting started<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/design/index.html">Introduction to Apache Druid</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/tutorials/index.html">Quickstart</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/single-server.html">Single server deployment</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/tutorials/cluster.html">Clustered deployment</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Tutorials<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/tutorials/tutorial-batch.html">Loading files natively</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/tutorials/tutorial-kafka.html">Load from Apache Kafka</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/tutorials/tutorial-batch-hadoop.html">Load from Apache Hadoop</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/tutorials/tutorial-query.html">Querying data</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/tutorials/tutorial-rollup.html">Roll-up</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/tutorials/tutorial-retention.html">Configuring data retention</a></li><li 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class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/ingestion/index.html">Ingestion</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/ingestion/data-formats.html">Data formats</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/ingestion/schema-design.html">Schema design tips</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/ingestion/data-management.html">Data management</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Stream ingestion</h4><ul><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/kafka-ingestion.html">Apache Kafka</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/kinesis-ingestion.html">Amazon Kinesis</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/ingestion/tranquility.html">Tranquility</a></li></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Batch ingestion</h4><ul><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/ingestion/native-batch.html">Native batch</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/ingestion/hadoop.html">Hadoop-based</a></li></ul></div><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/ingestion/tasks.html">Task reference</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/ingestion/faq.html">Troubleshooting FAQ</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Querying<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" 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href="/docs/0.16.1-incubating/querying/timeboundaryquery.html">TimeBoundary</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/segmentmetadataquery.html">SegmentMetadata</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/datasourcemetadataquery.html">DatasourceMetadata</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/searchquery.html">Search</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/select-query.html">Select</a></li></ul></div><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/multi-value-dimensions.html">Multi-value dimensions</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/lookups.html">Lookups</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/joins.html">Joins</a></li><li class="navListItem"><a 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href="/docs/0.16.1-incubating/configuration/logging.html">Logging</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Operations<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/management-uis.html">Management UIs</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/basic-cluster-tuning.html">Basic cluster tuning</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/api-reference.html">API reference</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/high-availability.html">High availability</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/rolling-updates.html">Rolling updates</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/rule-configuration.html">Retaining or automatically dropping data</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/metrics.html">Metrics</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/alerts.html">Alerts</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/other-hadoop.html">Working with different versions of Apache Hadoop</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/http-compression.html">HTTP compression</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/recommendations.html">Recommendations</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/tls-support.html">TLS support</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/password-provider.html">Password providers</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/dump-segment.html">dump-segment tool</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/reset-cluster.html">reset-cluster tool</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/insert-segment-to-db.html">insert-segment-to-db tool</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/pull-deps.html">pull-deps tool</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Misc</h4><ul><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/deep-storage-migration.html">Deep storage migration</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/druid-console.html">Web console</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/export-metadata.html">Export Metadata Tool</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/getting-started.html">Getting started with Apache Druid</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/metadata-migration.html">Metadata Migration</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/segment-optimization.html">Segment Size Optimization</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/operations/use_sbt_to_build_fat_jar.html">Content for build.sbt</a></li></ul></div></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Development<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/overview.html">Developing on Druid</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/modules.html">Creating extensions</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/javascript.html">JavaScript functionality</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/build.html">Build from source</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/versioning.html">Versioning</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/experimental.html">Experimental features</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Misc<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/misc/math-expr.html">Expressions</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/misc/papers-and-talks.html">Papers</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Hidden<span class="arrow"><svg width="24" height="24" viewBox="0 0 24 24"><path fill="#565656" d="M7.41 15.41L12 10.83l4.59 4.58L18 14l-6-6-6 6z"></path><path d="M0 0h24v24H0z" fill="none"></path></svg></span></h3><ul class="hide"><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/comparisons/druid-vs-elasticsearch.html">Apache Druid vs Elasticsearch</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/comparisons/druid-vs-key-value.html">Apache Druid vs. Key/Value Stores (HBase/Cassandra/OpenTSDB)</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/comparisons/druid-vs-kudu.html">Apache Druid vs Kudu</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/comparisons/druid-vs-redshift.html">Apache Druid vs Redshift</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/comparisons/druid-vs-spark.html">Apache Druid vs Spark</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/comparisons/druid-vs-sql-on-hadoop.html">Apache Druid vs SQL-on-Hadoop</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/design/auth.html">Authentication and Authorization</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/design/broker.html">Broker</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/design/coordinator.html">Coordinator Process</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/design/historical.html">Historical Process</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/design/indexer.html">Indexer Process</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/design/indexing-service.html">Indexing Service</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/design/middlemanager.html">MiddleManager Process</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/design/overlord.html">Overlord Process</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/design/router.html">Router Process</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/design/peons.html">Peons</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/approximate-histograms.html">Approximate Histogram aggregators</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/avro.html">Apache Avro</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/bloom-filter.html">Bloom Filter</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/datasketches-extension.html">DataSketches extension</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/datasketches-hll.html">DataSketches HLL Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/datasketches-quantiles.html">DataSketches Quantiles Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/datasketches-theta.html">DataSketches Theta Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/datasketches-tuple.html">DataSketches Tuple Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/druid-basic-security.html">Basic Security</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/druid-kerberos.html">Kerberos</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/druid-lookups.html">Cached Lookup Module</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/google.html">Google Cloud Storage</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/hdfs.html">HDFS</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/kafka-extraction-namespace.html">Apache Kafka Lookups</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/lookups-cached-global.html">Globally Cached Lookups</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/mysql.html">MySQL Metadata Store</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/orc.html">ORC Extension</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/parquet.html">Apache Parquet Extension</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/postgresql.html">PostgreSQL Metadata Store</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/protobuf.html">Protobuf</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/s3.html">S3-compatible</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/simple-client-sslcontext.html">Simple SSLContext Provider Module</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/stats.html">Stats aggregator</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-core/test-stats.html">Test Stats Aggregators</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-contrib/ambari-metrics-emitter.html">Ambari Metrics Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-contrib/azure.html">Microsoft Azure</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-contrib/cassandra.html">Apache Cassandra</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-contrib/cloudfiles.html">Rackspace Cloud Files</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-contrib/distinctcount.html">DistinctCount Aggregator</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-contrib/graphite.html">Graphite Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/aggregations.html">Aggregations</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/datasource.html">Datasources</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/dimensionspecs.html">Transforming Dimension Values</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/filters.html">Query Filters</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/granularities.html">Aggregation Granularity</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/having.html">Filter groupBy query results</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/hll-old.html">Cardinality/HyperUnique aggregators</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/limitspec.html">Sort groupBy query results</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/post-aggregations.html">Post-Aggregations</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/query-context.html">Query context</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/searchqueryspec.html">Refining search queries</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/sorting-orders.html">Sorting Orders</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/topnmetricspec.html">TopNMetricSpec</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/querying/virtual-columns.html">Virtual Columns</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-contrib/influx.html">InfluxDB Line Protocol Parser</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-contrib/influxdb-emitter.html">InfluxDB Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/0.16.1-incubating/development/extensions-contrib/kafka-emitter.html">Kafka Emitter</a></li><li 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<p>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.</p>
<p>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.</p>
<h2><a class="anchor" aria-hidden="true" id="core-extensions"></a><a href="#core-extensions" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Core extensions</h2>
<p>Core extensions are maintained by Druid committers.</p>
<table>
<thead>
<tr><th>Name</th><th>Description</th><th>Docs</th></tr>
</thead>
<tbody>
<tr><td>druid-avro-extensions</td><td>Support for data in Apache Avro data format.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/avro.html">link</a></td></tr>
<tr><td>druid-basic-security</td><td>Support for Basic HTTP authentication and role-based access control.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/druid-basic-security.html">link</a></td></tr>
<tr><td>druid-bloom-filter</td><td>Support for providing Bloom filters in druid queries.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/bloom-filter.html">link</a></td></tr>
<tr><td>druid-caffeine-cache</td><td>A local cache implementation backed by Caffeine.</td><td><a href="/docs/0.16.1-incubating/configuration/index.html#cache-configuration">link</a></td></tr>
<tr><td>druid-datasketches</td><td>Support for approximate counts and set operations with <a href="https://datasketches.github.io/">DataSketches</a>.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/datasketches-extension.html">link</a></td></tr>
<tr><td>druid-google-extensions</td><td>Google Cloud Storage deep storage.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/google.html">link</a></td></tr>
<tr><td>druid-hdfs-storage</td><td>HDFS deep storage.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/hdfs.html">link</a></td></tr>
<tr><td>druid-histogram</td><td>Approximate histograms and quantiles aggregator. Deprecated, please use the <a href="/docs/0.16.1-incubating/development/extensions-core/datasketches-quantiles.html">DataSketches quantiles aggregator</a> from the <code>druid-datasketches</code> extension instead.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/approximate-histograms.html">link</a></td></tr>
<tr><td>druid-kafka-extraction-namespace</td><td>Kafka-based namespaced lookup. Requires namespace lookup extension.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/kafka-extraction-namespace.html">link</a></td></tr>
<tr><td>druid-kafka-indexing-service</td><td>Supervised exactly-once Kafka ingestion for the indexing service.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/kafka-ingestion.html">link</a></td></tr>
<tr><td>druid-kinesis-indexing-service</td><td>Supervised exactly-once Kinesis ingestion for the indexing service.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/kinesis-ingestion.html">link</a></td></tr>
<tr><td>druid-kerberos</td><td>Kerberos authentication for druid processes.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/druid-kerberos.html">link</a></td></tr>
<tr><td>druid-lookups-cached-global</td><td>A module for <a href="/docs/0.16.1-incubating/querying/lookups.html">lookups</a> providing a jvm-global eager caching for lookups. It provides JDBC and URI implementations for fetching lookup data.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/lookups-cached-global.html">link</a></td></tr>
<tr><td>druid-lookups-cached-single</td><td>Per lookup caching module to support the use cases where a lookup need to be isolated from the global pool of lookups</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/druid-lookups.html">link</a></td></tr>
<tr><td>druid-orc-extensions</td><td>Support for data in Apache Orc data format.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/orc.html">link</a></td></tr>
<tr><td>druid-parquet-extensions</td><td>Support for data in Apache Parquet data format. Requires druid-avro-extensions to be loaded.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/parquet.html">link</a></td></tr>
<tr><td>druid-protobuf-extensions</td><td>Support for data in Protobuf data format.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/protobuf.html">link</a></td></tr>
<tr><td>druid-s3-extensions</td><td>Interfacing with data in AWS S3, and using S3 as deep storage.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/s3.html">link</a></td></tr>
<tr><td>druid-ec2-extensions</td><td>Interfacing with AWS EC2 for autoscaling middle managers</td><td>UNDOCUMENTED</td></tr>
<tr><td>druid-stats</td><td>Statistics related module including variance and standard deviation.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/stats.html">link</a></td></tr>
<tr><td>mysql-metadata-storage</td><td>MySQL metadata store.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/mysql.html">link</a></td></tr>
<tr><td>postgresql-metadata-storage</td><td>PostgreSQL metadata store.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/postgresql.html">link</a></td></tr>
<tr><td>simple-client-sslcontext</td><td>Simple SSLContext provider module to be used by Druid's internal HttpClient when talking to other Druid processes over HTTPS.</td><td><a href="/docs/0.16.1-incubating/development/extensions-core/simple-client-sslcontext.html">link</a></td></tr>
</tbody>
</table>
<h2><a class="anchor" aria-hidden="true" id="community-extensions"></a><a href="#community-extensions" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Community extensions</h2>
<blockquote>
<p>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.</p>
</blockquote>
<p>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 <a href="https://lists.apache.org/list.html?dev@druid.apache.org">dev@druid.apache.org</a> to let us know!</p>
<p>All of these community extensions can be downloaded using <a href="/docs/0.16.1-incubating/operations/pull-deps.html">pull-deps</a> while specifying a <code>-c</code> coordinate option to pull <code>org.apache.druid.extensions.contrib:{EXTENSION_NAME}:{DRUID_VERSION}</code>.</p>
<table>
<thead>
<tr><th>Name</th><th>Description</th><th>Docs</th></tr>
</thead>
<tbody>
<tr><td>ambari-metrics-emitter</td><td>Ambari Metrics Emitter</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/ambari-metrics-emitter.html">link</a></td></tr>
<tr><td>druid-azure-extensions</td><td>Microsoft Azure deep storage.</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/azure.html">link</a></td></tr>
<tr><td>druid-cassandra-storage</td><td>Apache Cassandra deep storage.</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/cassandra.html">link</a></td></tr>
<tr><td>druid-cloudfiles-extensions</td><td>Rackspace Cloudfiles deep storage and firehose.</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/cloudfiles.html">link</a></td></tr>
<tr><td>druid-distinctcount</td><td>DistinctCount aggregator</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/distinctcount.html">link</a></td></tr>
<tr><td>druid-redis-cache</td><td>A cache implementation for Druid based on Redis.</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/redis-cache.html">link</a></td></tr>
<tr><td>druid-time-min-max</td><td>Min/Max aggregator for timestamp.</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/time-min-max.html">link</a></td></tr>
<tr><td>sqlserver-metadata-storage</td><td>Microsoft SQLServer deep storage.</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/sqlserver.html">link</a></td></tr>
<tr><td>graphite-emitter</td><td>Graphite metrics emitter</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/graphite.html">link</a></td></tr>
<tr><td>statsd-emitter</td><td>StatsD metrics emitter</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/statsd.html">link</a></td></tr>
<tr><td>kafka-emitter</td><td>Kafka metrics emitter</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/kafka-emitter.html">link</a></td></tr>
<tr><td>druid-thrift-extensions</td><td>Support thrift ingestion</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/thrift.html">link</a></td></tr>
<tr><td>druid-opentsdb-emitter</td><td>OpenTSDB metrics emitter</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/opentsdb-emitter.html">link</a></td></tr>
<tr><td>materialized-view-selection, materialized-view-maintenance</td><td>Materialized View</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/materialized-view.html">link</a></td></tr>
<tr><td>druid-moving-average-query</td><td>Support for <a href="https://en.wikipedia.org/wiki/Moving_average">Moving Average</a> and other Aggregate <a href="https://en.wikibooks.org/wiki/Structured_Query_Language/Window_functions">Window Functions</a> in Druid queries.</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/moving-average-query.html">link</a></td></tr>
<tr><td>druid-influxdb-emitter</td><td>InfluxDB metrics emitter</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/influxdb-emitter.html">link</a></td></tr>
<tr><td>druid-momentsketch</td><td>Support for approximate quantile queries using the <a href="https://github.com/stanford-futuredata/momentsketch">momentsketch</a> library</td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/momentsketch-quantiles.html">link</a></td></tr>
<tr><td>druid-tdigestsketch</td><td>Support for approximate sketch aggregators based on <a href="https://github.com/tdunning/t-digest">T-Digest</a></td><td><a href="/docs/0.16.1-incubating/development/extensions-contrib/tdigestsketch-quantiles.html">link</a></td></tr>
</tbody>
</table>
<h2><a class="anchor" aria-hidden="true" id="promoting-community-extensions-to-core-extensions"></a><a href="#promoting-community-extensions-to-core-extensions" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Promoting community extensions to core extensions</h2>
<p>Please post on <a href="https://lists.apache.org/list.html?dev@druid.apache.org">dev@druid.apache.org</a> 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.</p>
<p>For information how to create your own extension, please see <a href="/docs/0.16.1-incubating/development/modules.html">here</a>.</p>
<h2><a class="anchor" aria-hidden="true" id="loading-extensions"></a><a href="#loading-extensions" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Loading extensions</h2>
<h3><a class="anchor" aria-hidden="true" id="loading-core-extensions"></a><a href="#loading-core-extensions" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Loading core extensions</h3>
<p>Apache Druid (incubating) bundles all <a href="/docs/0.16.1-incubating/development/extensions.html#core-extensions">core extensions</a> out of the box.
See the <a href="/docs/0.16.1-incubating/development/extensions.html#core-extensions">list of extensions</a> for your options. You
can load bundled extensions by adding their names to your common.runtime.properties
<code>druid.extensions.loadList</code> property. For example, to load the <em>postgresql-metadata-storage</em> and
<em>druid-hdfs-storage</em> extensions, use the configuration:</p>
<pre><code class="hljs">druid<span class="hljs-selector-class">.extensions</span><span class="hljs-selector-class">.loadList</span>=[<span class="hljs-string">"postgresql-metadata-storage"</span>, <span class="hljs-string">"druid-hdfs-storage"</span>]
</code></pre>
<p>These extensions are located in the <code>extensions</code> directory of the distribution.</p>
<blockquote>
<p>Druid bundles two sets of configurations: one for the <a href="/docs/0.16.1-incubating/tutorials/index.html">quickstart</a> and
one for a <a href="/docs/0.16.1-incubating/tutorials/cluster.html">clustered configuration</a>. Make sure you are updating the correct
common.runtime.properties for your setup.</p>
</blockquote>
<blockquote>
<p>Because of licensing, the mysql-metadata-storage extension does not include the required MySQL JDBC driver. For instructions
on how to install this library, see the <a href="/docs/0.16.1-incubating/development/extensions-core/mysql.html">MySQL extension page</a>.</p>
</blockquote>
<h3><a class="anchor" aria-hidden="true" id="loading-community-extensions"></a><a href="#loading-community-extensions" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Loading community extensions</h3>
<p>You can also load community and third-party extensions not already bundled with Druid. To do this, first download the extension and
then install it into your <code>extensions</code> directory. You can download extensions from their distributors directly, or
if they are available from Maven, the included <a href="/docs/0.16.1-incubating/operations/pull-deps.html">pull-deps</a> can download them for you. To use <em>pull-deps</em>,
specify the full Maven coordinate of the extension in the form <code>groupId:artifactId:version</code>. For example,
for the (hypothetical) extension <em>com.example:druid-example-extension:1.0.0</em>, run:</p>
<pre><code class="hljs">java \
  -cp <span class="hljs-string">"lib/*"</span> \
  -Ddruid<span class="hljs-selector-class">.extensions</span><span class="hljs-selector-class">.directory</span>=<span class="hljs-string">"extensions"</span> \
  -Ddruid<span class="hljs-selector-class">.extensions</span><span class="hljs-selector-class">.hadoopDependenciesDir</span>=<span class="hljs-string">"hadoop-dependencies"</span> \
  org<span class="hljs-selector-class">.apache</span><span class="hljs-selector-class">.druid</span><span class="hljs-selector-class">.cli</span><span class="hljs-selector-class">.Main</span> tools pull-deps \
  --no-default-hadoop \
  -c <span class="hljs-string">"com.example:druid-example-extension:1.0.0"</span>
</code></pre>
<p>You only have to install the extension once. Then, add <code>&quot;druid-example-extension&quot;</code> to
<code>druid.extensions.loadList</code> in common.runtime.properties to instruct Druid to load the extension.</p>
<blockquote>
<p>Please make sure all the Extensions related configuration properties listed <a href="/docs/0.16.1-incubating/configuration/index.html#extensions">here</a> are set correctly.</p>
</blockquote>
<blockquote>
<p>The Maven groupId for almost every <a href="/docs/0.16.1-incubating/development/extensions.html#community-extensions">community extension</a> is org.apache.druid.extensions.contrib. The artifactId is the name
of the extension, and the version is the latest Druid stable version.</p>
</blockquote>
<h3><a class="anchor" aria-hidden="true" id="loading-extensions-from-the-classpath"></a><a href="#loading-extensions-from-the-classpath" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Loading extensions from the classpath</h3>
<p>If you add your extension jar to the classpath at runtime, Druid will also load it into the system.  This mechanism is relatively easy to reason about,
but it also means that you have to ensure that all dependency jars on the classpath are compatible.  That is, Druid makes no provisions while using
this method to maintain class loader isolation so you must make sure that the jars on your classpath are mutually compatible.</p>
</span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/0.16.1-incubating/configuration/index.html"><span class="arrow-prev">← </span><span>Configuration reference</span></a><a class="docs-next button" href="/docs/0.16.1-incubating/configuration/logging.html"><span>Logging</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#core-extensions">Core extensions</a></li><li><a href="#community-extensions">Community extensions</a></li><li><a href="#promoting-community-extensions-to-core-extensions">Promoting community extensions to core extensions</a></li><li><a href="#loading-extensions">Loading extensions</a><ul class="toc-headings"><li><a href="#loading-core-extensions">Loading core extensions</a></li><li><a href="#loading-community-extensions">Loading community extensions</a></li><li><a href="#loading-extensions-from-the-classpath">Loading extensions from the classpath</a></li></ul></li></ul></nav></div><footer class="nav-footer druid-footer" id="footer"><div class="container"><div class="text-center"><p><a href="/technology">Technology</a> · <a href="/use-cases">Use Cases</a> · <a href="/druid-powered">Powered by Druid</a> · <a href="/docs/0.16.1-incubating/latest">Docs</a> · <a href="/community/">Community</a> · <a href="/downloads.html">Download</a> · <a href="/faq">FAQ</a></p></div><div class="text-center"><a title="Join the user group" href="https://groups.google.com/forum/#!forum/druid-user" target="_blank"><span class="fa fa-comments"></span></a> · <a title="Follow Druid" href="https://twitter.com/druidio" target="_blank"><span class="fab fa-twitter"></span></a> · <a title="Download via Apache" href="https://www.apache.org/dyn/closer.cgi?path=/incubator/druid/{{ site.druid_versions[0].versions[0].version }}/apache-druid-{{ site.druid_versions[0].versions[0].version }}-bin.tar.gz" target="_blank"><span class="fas fa-feather"></span></a> · <a title="GitHub" href="https://github.com/apache/incubator-druid" target="_blank"><span class="fab fa-github"></span></a></div><div class="text-center license">Copyright © 2019 <a href="https://www.apache.org/" target="_blank">Apache Software Foundation</a>.<br/>Except where otherwise noted, licensed under <a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA 4.0</a>.<br/>Apache Druid, Druid, and the Druid logo are either registered trademarks or trademarks of The Apache Software Foundation in the United States and other countries.</div></div></footer></div><script type="text/javascript" src="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.js"></script><script>
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