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Getting started

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

Tutorials

  • Load files natively
  • Load files using SQL ๐Ÿ†•
  • Load from Apache Kafka
  • Load from Apache Hadoop
  • Querying data
  • Roll-up
  • Theta sketches
  • Configuring data retention
  • Updating existing data
  • Compacting segments
  • Deleting data
  • Writing an ingestion spec
  • Transforming input data
  • Tutorial: Run with Docker
  • Kerberized HDFS deep storage
  • Convert ingestion spec to SQL
  • Jupyter Notebook tutorials

Design

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

Ingestion

  • Ingestion
  • Data formats
  • Data model
  • Data rollup
  • Partitioning
  • Ingestion spec
  • Schema design tips
  • Stream ingestion

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

    Batch ingestion

    • Native batch
    • Native batch: input sources
    • Migrate from firehose
    • Hadoop-based

    SQL-based ingestion ๐Ÿ†•

    • Overview
    • Key concepts
    • API
    • Security
    • Examples
    • Reference
    • Known issues
  • Task reference
  • Troubleshooting FAQ

Data management

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

Querying

    Druid SQL

    • Overview and syntax
    • SQL data types
    • Operators
    • Scalar functions
    • Aggregation functions
    • Multi-value string functions
    • JSON functions
    • All functions
    • Druid SQL API
    • JDBC driver API
    • 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

Configuration

  • Configuration reference
  • Extensions
  • Logging

Operations

  • Web console
  • Java runtime
  • 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
  • API reference
  • High availability
  • Rolling updates
  • Using rules to drop and retain data
  • 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
  • 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
  • kubernetes
  • Cardinality/HyperUnique aggregators
  • Select
  • Firehose (deprecated)
  • Native batch (simple)
  • Realtime Process
Edit

Kubernetes

Consider this an EXPERIMENTAL feature mostly because it has not been tested yet on a wide variety of long running Druid clusters.

Apache Druid Extension to enable using Kubernetes API Server for node discovery and leader election. This extension allows Druid cluster deployment on Kubernetes without Zookeeper. It allows running multiple Druid clusters within same Kubernetes Cluster, See clusterIdentifier config below.

Configuration

To use this extension please make sure to include druid-kubernetes-extensions in the extensions load list.

This extension works together with HTTP based segment and task management in Druid. Consequently, following configurations must be set on all Druid nodes.

druid.zk.service.enabled=false druid.serverview.type=http druid.coordinator.loadqueuepeon.type=http druid.indexer.runner.type=httpRemote druid.discovery.type=k8s

For Node Discovery, Each Druid process running inside a pod "announces" itself by adding few "labels" and "annotations" in the pod spec. Druid process needs to be aware of pod name and namespace which it reads from environment variables POD_NAME and POD_NAMESPACE. These variable names can be changed, see configuration below. But in the end, each pod needs to have self pod name and namespace added as environment variables.

Additionally, this extension has following configuration.

Properties

PropertyPossible ValuesDescriptionDefaultrequired
druid.discovery.k8s.clusterIdentifierstring that matches [a-z0-9][a-z0-9-]*[a-z0-9]Unique identifier for this Druid cluster in Kubernetes e.g. us-west-prod-druid.NoneYes
druid.discovery.k8s.podNameEnvKeyPod Env VariablePod Env variable whose value is that pod's name.POD_NAMENo
druid.discovery.k8s.podNamespaceEnvKeyPod Env VariablePod Env variable whose value is that pod's kubernetes namespace.POD_NAMESPACENo
druid.discovery.k8s.leaseDurationDurationLease duration used by Leader Election algorithm. Candidates wait for this time before taking over previous Leader.PT60SNo
druid.discovery.k8s.renewDeadlineDurationLease renewal period used by Leader.PT17SNo
druid.discovery.k8s.retryPeriodDurationRetry wait used by Leader Election algorithm on failed operations.PT5SNo

Gotchas

  • Label/Annotation path in each pod spec MUST EXIST, which is easily satisfied if there is at least one label/annotation in the pod spec already. This limitation may be removed in future.
  • All Druid Pods belonging to one Druid cluster must be inside same kubernetes namespace.
  • All Druid Pods need permissions to be able to add labels to self-pod, List and Watch other Pods, create and read ConfigMap for leader election. Assuming, "default" service account is used by Druid pods, you might need to add following or something similar Kubernetes Role and Role Binding.
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: druid-cluster
rules:
- apiGroups:
  - ""
  resources:
  - pods
  - configmaps
  verbs:
  - '*'
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: druid-cluster
subjects:
- kind: ServiceAccount
  name: default
roleRef:
  kind: Role
  name: druid-cluster
  apiGroup: rbac.authorization.k8s.io
โ† Druid AWS RDS ModuleAmbari Metrics Emitter โ†’
  • Configuration
    • Properties
    • Gotchas

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Copyright ยฉ 2022 Apache Software Foundation.
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