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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
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    • API
    • Security
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    • Known issues
  • Task reference
  • Troubleshooting FAQ

Data management

  • Overview
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  • 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
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    • Multi-value dimensions
    • Nested columns
    • Multitenancy
    • Query caching
    • Using query caching
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    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)
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Configuration

  • Configuration reference
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Operations

  • Web console
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    • Security overview
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    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
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    • pull-deps tool
    • Deep storage migration
    • Export Metadata Tool
    • Metadata Migration
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Development

  • Developing on Druid
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Misc

  • Papers

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  • Apache Druid vs Elasticsearch
  • Apache Druid vs. Key/Value Stores (HBase/Cassandra/OpenTSDB)
  • Apache Druid vs Kudu
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  • Apache Druid vs Spark
  • Apache Druid vs SQL-on-Hadoop
  • Authentication and Authorization
  • Broker
  • Coordinator Process
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  • Apache Avro
  • Microsoft Azure
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  • DataSketches extension
  • DataSketches HLL Sketch module
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  • Basic Security
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  • Druid AWS RDS Module
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  • Graphite Emitter
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  • Moment Sketches for Approximate Quantiles module
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  • Microsoft SQLServer
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  • GCE Extensions
  • Aliyun OSS
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  • kubernetes
  • Cardinality/HyperUnique aggregators
  • Select
  • Firehose (deprecated)
  • Native batch (simple)
  • Realtime Process
Edit

Druid Redis Cache

A cache implementation for Druid based on Redis.

Below are guidance and configuration options known to this module.

Installation

Use pull-deps tool shipped with Druid to install this extension on broker, historical and middle manager nodes.

java -classpath "druid_dir/lib/*" org.apache.druid.cli.Main tools pull-deps -c org.apache.druid.extensions.contrib:druid-redis-cache:{VERSION}

Enabling

To enable this extension after installation,

  1. include this druid-redis-cache extension
  2. to enable cache on broker nodes, follow broker caching docs to set related properties
  3. to enable cache on historical nodes, follow historical caching docs to set related properties
  4. to enable cache on middle manager nodes, follow peon caching docs to set related properties
  5. set druid.cache.type to redis
  6. add the following properties

Configuration

Cluster mode

To utilize a redis cluster, following properties must be set.

Note: some redis cloud service providers provide redis cluster service via a redis proxy, for these clusters, please follow the Standalone mode configuration below.

PropertiesDescriptionDefaultRequired
druid.cache.cluster.nodesRedis nodes in a cluster, represented in comma separated string. See example belowNoneyes
druid.cache.cluster.maxRedirectionMax retry count5no

Example

# a typical redis cluster with 6 nodes
druid.cache.cluster.nodes=127.0.0.1:7001,127.0.0.1:7002,127.0.0.1:7003,127.0.0.1:7004,127.0.0.1:7005,127.0.0.1:7006

Standalone mode

To use a standalone redis, following properties must be set.

PropertiesDescriptionDefaultRequired
druid.cache.hostRedis server hostNoneyes
druid.cache.portRedis server portNoneyes
druid.cache.databaseRedis database index0no

Note: if both druid.cache.cluster.nodes and druid.cache.host are provided, cluster mode is preferred.

Shared Properties

Except for the properties above, there are some extra properties which can be customized to meet different needs.

PropertiesDescriptionDefaultRequired
druid.cache.passwordPassword to access redis server/clusterNoneno
druid.cache.expirationExpiration for cache entriesP1Dno
druid.cache.timeoutTimeout for connecting to Redis and reading entries from RedisPT2Sno
druid.cache.maxTotalConnectionsMax total connections to Redis8no
druid.cache.maxIdleConnectionsMax idle connections to Redis8no
druid.cache.minIdleConnectionsMin idle connections to Redis0no

For druid.cache.expiration and druid.cache.timeout properties, values can be format of Period or a number in milliseconds.

# Period format(recomended)
# cache expires after 1 hour
druid.cache.expiration=PT1H

# or in number(milliseconds) format
# 1 hour = 3_600_000 milliseconds
druid.cache.expiration=3600000

Metrics

In addition to the normal cache metrics, the redis cache implementation also reports the following in both total and delta

MetricDescriptionNormal value
query/cache/redis/*/requestsCount of requests to redis cachewhatever request to redis will increase request count by 1
โ† OpenTSDB EmitterMicrosoft SQLServer โ†’
  • Installation
  • Enabling
  • Configuration
    • Cluster mode
    • Standalone mode
    • Shared Properties
  • Metrics

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