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Getting started

  • Introduction to Apache Druid
  • Quickstart (local)
  • Single server deployment
  • Clustered deployment

Tutorials

  • Load files using SQL
  • Load from Apache Kafka
  • Load from Apache Hadoop
  • Query data
  • Aggregate data with rollup
  • Theta sketches
  • Configure data retention
  • Update existing data
  • Compact segments
  • Deleting data
  • Write an ingestion spec
  • Transform input data
  • Convert ingestion spec to SQL
  • Run with Docker
  • Kerberized HDFS deep storage
  • Get to know Query view
  • Unnesting arrays
  • Query from deep storage
  • Jupyter Notebook tutorials
  • Docker for tutorials
  • JDBC connector

Design

  • Design
  • Segments
  • Processes and servers
  • Deep storage
  • Metadata storage
  • ZooKeeper

Ingestion

  • Overview
  • Ingestion concepts

    • Source input formats
    • Input sources
    • Schema model
    • Rollup
    • Partitioning
    • Task reference

    SQL-based batch

    • SQL-based ingestion
    • Key concepts
    • Security
    • Examples
    • Reference
    • Known issues

    Streaming

    • Apache Kafka ingestion
    • Apache Kafka supervisor
    • Apache Kafka operations
    • Amazon Kinesis

    Classic batch

    • JSON-based batch
    • Hadoop-based
  • Ingestion spec reference
  • Schema design tips
  • Troubleshooting FAQ

Data management

  • Overview
  • Data updates
  • Data deletion
  • Schema changes
  • Compaction
  • Automatic compaction

Querying

    Druid SQL

    • Overview and syntax
    • Query from deep storage
    • SQL data types
    • Operators
    • Scalar functions
    • Aggregation functions
    • Array functions
    • Multi-value string functions
    • JSON functions
    • All functions
    • SQL query context
    • SQL metadata tables
    • SQL query translation
  • Native queries
  • Query execution
  • Troubleshooting
  • Concepts

    • Datasources
    • Joins
    • Lookups
    • Multi-value dimensions
    • Nested columns
    • Multitenancy
    • Query caching
    • Using query caching
    • Query context

    Native query types

    • Timeseries
    • TopN
    • GroupBy
    • Scan
    • Search
    • TimeBoundary
    • SegmentMetadata
    • DatasourceMetadata

    Native query components

    • Filters
    • Granularities
    • Dimensions
    • Aggregations
    • Post-aggregations
    • Expressions
    • Having filters (groupBy)
    • Sorting and limiting (groupBy)
    • Sorting (topN)
    • String comparators
    • Virtual columns
    • Spatial filters

API reference

  • Overview
  • HTTP APIs

    • Druid SQL
    • SQL-based ingestion
    • JSON querying
    • Tasks
    • Supervisors
    • Retention rules
    • Data management
    • Automatic compaction
    • Lookups
    • Service status
    • Dynamic configuration
    • Legacy metadata

    Java APIs

    • SQL JDBC driver

Configuration

  • Configuration reference
  • Extensions
  • Logging

Operations

  • Web console
  • Java runtime
  • Durable storage
  • Security

    • Security overview
    • User authentication and authorization
    • LDAP auth
    • Password providers
    • Dynamic Config Providers
    • TLS support

    Performance tuning

    • Basic cluster tuning
    • Segment size optimization
    • Mixed workloads
    • HTTP compression
    • Automated metadata cleanup

    Monitoring

    • Request logging
    • Metrics
    • Alerts
  • High availability
  • Rolling updates
  • Using rules to drop and retain data
  • Migrate from firehose
  • Working with different versions of Apache Hadoop
  • Misc

    • dump-segment tool
    • reset-cluster tool
    • insert-segment-to-db tool
    • pull-deps tool
    • Deep storage migration
    • Export Metadata Tool
    • Metadata Migration
    • Content for build.sbt

Development

  • Developing on Druid
  • Creating extensions
  • JavaScript functionality
  • Build from source
  • Versioning
  • Contribute to Druid docs
  • Experimental features

Misc

  • Papers

Hidden

  • Apache Druid vs Elasticsearch
  • Apache Druid vs. Key/Value Stores (HBase/Cassandra/OpenTSDB)
  • Apache Druid vs Kudu
  • Apache Druid vs Redshift
  • Apache Druid vs Spark
  • Apache Druid vs SQL-on-Hadoop
  • Authentication and Authorization
  • Broker
  • Coordinator Process
  • Historical Process
  • Indexer Process
  • Indexing Service
  • MiddleManager Process
  • Overlord Process
  • Router Process
  • Peons
  • Approximate Histogram aggregators
  • Apache Avro
  • Microsoft Azure
  • Bloom Filter
  • DataSketches extension
  • DataSketches HLL Sketch module
  • DataSketches Quantiles Sketch module
  • DataSketches Theta Sketch module
  • DataSketches Tuple Sketch module
  • Basic Security
  • Kerberos
  • Cached Lookup Module
  • Apache Ranger Security
  • Google Cloud Storage
  • HDFS
  • Apache Kafka Lookups
  • Globally Cached Lookups
  • MySQL Metadata Store
  • ORC Extension
  • Druid pac4j based Security extension
  • Apache Parquet Extension
  • PostgreSQL Metadata Store
  • Protobuf
  • S3-compatible
  • Simple SSLContext Provider Module
  • Stats aggregator
  • Test Stats Aggregators
  • Druid AWS RDS Module
  • Kubernetes
  • Ambari Metrics Emitter
  • Apache Cassandra
  • Rackspace Cloud Files
  • DistinctCount Aggregator
  • Graphite Emitter
  • InfluxDB Line Protocol Parser
  • InfluxDB Emitter
  • Kafka Emitter
  • Materialized View
  • Moment Sketches for Approximate Quantiles module
  • Moving Average Query
  • OpenTSDB Emitter
  • Druid Redis Cache
  • Microsoft SQLServer
  • StatsD Emitter
  • T-Digest Quantiles Sketch module
  • Thrift
  • Timestamp Min/Max aggregators
  • GCE Extensions
  • Aliyun OSS
  • Prometheus Emitter
  • Firehose (deprecated)
  • JSON-based batch (simple)
  • Realtime Process
  • kubernetes
  • Cardinality/HyperUnique aggregators
  • Select
  • Load files natively
Edit

Contribute to Druid docs

Apache Druid is a community-led project. We are delighted to receive contributions to the docs ranging from minor fixes to big new features.

Druid docs contributors:

  • Improve existing content
  • Create new content

Getting started

Druid docs contributors can open an issue about documentation, or contribute a change with a pull request (PR).

The open source Druid docs are located here: https://druid.apache.org/docs/latest/design/index.html

If you need to update a Druid doc, locate and update the doc in the Druid repo following the instructions below.

Druid repo branches

The Druid team works on the master branch and then branches for a release, such as 26.0.0.

See CONTRIBUTING.md for instructions on contributing to Apache Druid.

Before you begin

Before you can contribute to the Druid docs for the first time, you must complete the following steps:

  1. Fork the Druid repo. Your fork will be the origin remote.

  2. Clone your fork:

    git clone git@github.com:GITHUB_USERNAME/druid.git
    

    Replace GITHUB_USERNAME with your GitHub username.

  3. In the directory where you cloned your fork, set up apache/druid as your your remote upstream repo:

    git remote add upstream https://github.com/apache/druid.git
    
  4. Confirm that your fork shows up as the origin repo and apache/druid shows up as the upstream repo:

    git remote -v
    
  5. Verify that you have your email configured for GitHub:

    git config user.email
    

    If you need to set your email, see the GitHub instructions.

  6. Install Docusaurus so that you can build the site locally. Run either npm install or yarn install in the website directory.

Contributing

Before you contribute, make sure your local branch of master and the upstream Apache branch are up-to-date and in sync. This can help you avoid merge conflicts. Run the following commands on your fork's master branch:

git fetch origin
git fetch upstream

Then run either one of the following commands:

git rebase upstream/master
# or
git merge upstream/master

Now you're up to date, and you can make your changes.

  1. Create your working branch:

    git checkout -b MY-BRANCH
    

Provide a name for your feature branch in MY-BRANCH.

  1. Find the file that you want to make changes to. All the source files for the docs are written in Markdown and located in the docs directory. The URL for the page includes the subdirectory the source file is in. For example, the SQL-based ingestion tutorial found at https://druid.apache.org/docs/latest/tutorials/tutorial-msq-extern.html is in the tutorials subdirectory.

    If you're adding a page, create a new Markdown file in the appropriate subdirectory. Then, copy the front matter and Apache license from an existing file. Update the title and id fields. Don't forget to add it to website/sidebars.json so that your new page shows up in the navigation.

  2. Test changes locally by building the site and navigating to your changes. In the website directory, run docusaurus-start. By default, this starts the site on localhost:3000. If port 3000 is already in use, it'll increment the port number from there.

  3. Use the following commands to run the link and spellcheckers locally:

    npm run spellcheck
    npm run link-lint
    

    This step can save you time during the review process since they'll run faster than the GitHub Action version of the checks and warn you of issues before you create a PR.

  4. Push your changes to your fork:

    git push --set-upstream origin MY-BRANCH
    
  5. Go to the Druid repo. GitHub should recognize that you have a new branch in your fork. Create a pull request from your Druid fork and branch to the master branch in the Apache Druid repo.

The pull request template is extensive. You may not need all the information there, so feel free to delete unneeded sections as you fill it out. Once you create the pull request, GitHub automatically labels the issue so that reviewers can take a look.

The docs go through a review process similar to the code where community members will offer feedback. Once the review process is complete and your changes are merged, they'll be available on the live site when the site gets republished.

Style guide

Before publishing new content or updating an existing topic, audit your documentation using this checklist to make sure your contributions align with existing documentation.

Here are some general guidelines:

  • Use descriptive link text. If a link downloads a file, make sure to indicate this action.
  • Use present tense where possible.
  • Avoid negative constructions when possible. In other words, try to tell people what they should do instead of what they shouldn't.
  • Use clear and direct language.
  • Use descriptive headings and titles.
  • Avoid using a present participle or gerund as the first word in a heading or title. A shortcut for this is to not start with a word that ends in -ing. For example, don't use "Configuring Druid." Use "Configure Druid."
  • Use sentence case in document titles and headings.
  • Don’t use images of text or code samples.
  • Use SVG over PNG for images if you can.
  • Provide alt text or an equivalent text explanation with each image.
  • Use the appropriate text-formatting. For example, make sure code snippets and property names are in code font and UI elements are bold. Generally, you should avoid using bold or italics to emphasize certain words unless there's a good reason.
  • Put conditional clauses before instructions. In the following example, "to drop a segment" is the conditional clause: to drop a segment, do the following.
  • Avoid gender-specific pronouns, instead use "they."
  • Use second person singular — "you" instead of "we."
  • When American spelling is different from Commonwealth/"British" spelling, use the American spelling.
  • Don’t use terms considered disrespectful. Refer to a list like Google’s Word list for guidance and alternatives.
  • Use straight quotation marks and straight apostrophes instead of the curly versions.
  • Introduce a list, a table, or a procedure with an introductory sentence that prepares the reader for what they're about to read.
← VersioningExperimental features →
  • Getting started
  • Druid repo branches
  • Before you begin
  • Contributing
  • Style guide

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Copyright © 2022 Apache Software Foundation.
Except where otherwise noted, licensed under CC BY-SA 4.0.
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.