Google Git
Sign in
apache / druid-website / refs/heads/0.17.1-docs / . / docs / latest / development / extensions-core / approximate-histograms.html
blob: 1e0bd53d39b4faa58a11c67b8cd95761a2041a7f [file] [log] [blame]
<!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>Approximate Histogram aggregators · Apache Druid</title><meta name="viewport" content="width=device-width"/><link rel="canonical" href="https://druid.apache.org/docs/latest/development/extensions-core/approximate-histograms.html"/><meta name="generator" content="Docusaurus"/><meta name="description" content="&lt;!--"/><meta name="docsearch:language" content="en"/><meta name="docsearch:version" content="0.17.1" /><meta property="og:title" content="Approximate Histogram aggregators · 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>
window.dataLayer = window.dataLayer || [];
function gtag(){dataLayer.push(arguments); }
gtag('js', new Date());
gtag('config', 'UA-131010415-1');
</script><link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.7.2/css/all.css"/><link rel="stylesheet" href="/css/code-block-buttons.css"/><script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/clipboard.js/2.0.4/clipboard.min.js"></script><script type="text/javascript" src="/js/code-block-buttons.js"></script><script src="/js/scrollSpy.js"></script><link rel="stylesheet" href="/css/main.css"/><script src="/js/codetabs.js"></script></head><body class="sideNavVisible separateOnPageNav"><div class="fixedHeaderContainer"><div class="headerWrapper wrapper"><header><a href="/"><img class="logo" src="/img/druid_nav.png" alt="Apache Druid"/></a><div class="navigationWrapper navigationSlider"><nav class="slidingNav"><ul class="nav-site nav-site-internal"><li class=""><a href="/technology" target="_self">Technology</a></li><li class=""><a href="/use-cases" target="_self">Use Cases</a></li><li class=""><a href="/druid-powered" target="_self">Powered By</a></li><li class="siteNavGroupActive"><a href="/docs/latest/design/index.html" target="_self">Docs</a></li><li class=""><a href="/community/" target="_self">Community</a></li><li class=""><a href="https://www.apache.org" target="_self">Apache</a></li><li class=""><a href="/downloads.html" target="_self">Download</a></li><li class="navSearchWrapper reactNavSearchWrapper"><input type="text" id="search_input_react" placeholder="Search" title="Search"/></li></ul></nav></div></header></div></div><div class="navPusher"><div class="docMainWrapper wrapper"><div class="docsNavContainer" id="docsNav"><nav class="toc"><div class="toggleNav"><section class="navWrapper wrapper"><div class="navBreadcrumb wrapper"><div class="navToggle" id="navToggler"><div class="hamburger-menu"><div class="line1"></div><div class="line2"></div><div class="line3"></div></div></div><h2><i>›</i><span>Hidden</span></h2><div class="tocToggler" id="tocToggler"><i 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/latest/design/index.html">Introduction to Apache Druid</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/index.html">Quickstart</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/single-server.html">Single server deployment</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/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/latest/tutorials/tutorial-batch.html">Loading files natively</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/tutorial-kafka.html">Load from Apache Kafka</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/tutorial-batch-hadoop.html">Load from Apache Hadoop</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/tutorial-query.html">Querying data</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/tutorial-rollup.html">Roll-up</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/tutorial-retention.html">Configuring data retention</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/tutorial-update-data.html">Updating existing data</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/tutorial-compaction.html">Compacting segments</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/tutorial-delete-data.html">Deleting data</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/tutorial-ingestion-spec.html">Writing an ingestion spec</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/tutorial-transform-spec.html">Transforming input data</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/tutorials/tutorial-kerberos-hadoop.html">Kerberized HDFS deep storage</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Design<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/latest/design/architecture.html">Design</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/segments.html">Segments</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/processes.html">Processes and servers</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/dependencies/deep-storage.html">Deep storage</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/dependencies/metadata-storage.html">Metadata storage</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/dependencies/zookeeper.html">ZooKeeper</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Data ingestion<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/latest/ingestion/index.html">Ingestion</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/ingestion/data-formats.html">Data formats</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/ingestion/schema-design.html">Schema design tips</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/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/latest/development/extensions-core/kafka-ingestion.html">Apache Kafka</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/kinesis-ingestion.html">Amazon Kinesis</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/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/latest/ingestion/native-batch.html">Native batch</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/ingestion/hadoop.html">Hadoop-based</a></li></ul></div><li class="navListItem"><a class="navItem" href="/docs/latest/ingestion/tasks.html">Task reference</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/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" 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/latest/querying/sql.html">Druid SQL</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Native query types</h4><ul><li class="navListItem"><a class="navItem" href="/docs/latest/querying/querying.html">Making native queries</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/timeseriesquery.html">Timeseries</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/topnquery.html">TopN</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/groupbyquery.html">GroupBy</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/scan-query.html">Scan</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/timeboundaryquery.html">TimeBoundary</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/segmentmetadataquery.html">SegmentMetadata</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/datasourcemetadataquery.html">DatasourceMetadata</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/searchquery.html">Search</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/select-query.html">Select</a></li></ul></div><li class="navListItem"><a class="navItem" href="/docs/latest/querying/multi-value-dimensions.html">Multi-value dimensions</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/lookups.html">Lookups</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/joins.html">Joins</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/multitenancy.html">Multitenancy considerations</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/caching.html">Query caching</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/geo.html">Spatial filters</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Configuration<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/latest/configuration/index.html">Configuration reference</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions.html">Extensions</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/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/latest/operations/management-uis.html">Management UIs</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/basic-cluster-tuning.html">Basic cluster tuning</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/api-reference.html">API reference</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/high-availability.html">High availability</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/rolling-updates.html">Rolling updates</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/rule-configuration.html">Retaining or automatically dropping data</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/metrics.html">Metrics</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/alerts.html">Alerts</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/other-hadoop.html">Working with different versions of Apache Hadoop</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/http-compression.html">HTTP compression</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/tls-support.html">TLS support</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/password-provider.html">Password providers</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/dump-segment.html">dump-segment tool</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/reset-cluster.html">reset-cluster tool</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/insert-segment-to-db.html">insert-segment-to-db tool</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/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/latest/operations/deep-storage-migration.html">Deep storage migration</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/druid-console.html">Web console</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/export-metadata.html">Export Metadata Tool</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/getting-started.html">Getting started with Apache Druid</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/metadata-migration.html">Metadata Migration</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/operations/segment-optimization.html">Segment Size Optimization</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/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/latest/development/overview.html">Developing on Druid</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/modules.html">Creating extensions</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/javascript.html">JavaScript functionality</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/build.html">Build from source</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/versioning.html">Versioning</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/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/latest/misc/math-expr.html">Expressions</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/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/latest/comparisons/druid-vs-elasticsearch.html">Apache Druid vs Elasticsearch</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/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/latest/comparisons/druid-vs-kudu.html">Apache Druid vs Kudu</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/comparisons/druid-vs-redshift.html">Apache Druid vs Redshift</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/comparisons/druid-vs-spark.html">Apache Druid vs Spark</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/comparisons/druid-vs-sql-on-hadoop.html">Apache Druid vs SQL-on-Hadoop</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/auth.html">Authentication and Authorization</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/broker.html">Broker</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/coordinator.html">Coordinator Process</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/historical.html">Historical Process</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/indexer.html">Indexer Process</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/indexing-service.html">Indexing Service</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/middlemanager.html">MiddleManager Process</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/overlord.html">Overlord Process</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/router.html">Router Process</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/design/peons.html">Peons</a></li><li class="navListItem navListItemActive"><a class="navItem" href="/docs/latest/development/extensions-core/approximate-histograms.html">Approximate Histogram aggregators</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/avro.html">Apache Avro</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/bloom-filter.html">Bloom Filter</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/datasketches-extension.html">DataSketches extension</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/datasketches-hll.html">DataSketches HLL Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/datasketches-quantiles.html">DataSketches Quantiles Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/datasketches-theta.html">DataSketches Theta Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/datasketches-tuple.html">DataSketches Tuple Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/druid-basic-security.html">Basic Security</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/druid-kerberos.html">Kerberos</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/druid-lookups.html">Cached Lookup Module</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/google.html">Google Cloud Storage</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/hdfs.html">HDFS</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/kafka-extraction-namespace.html">Apache Kafka Lookups</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/lookups-cached-global.html">Globally Cached Lookups</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/mysql.html">MySQL Metadata Store</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/orc.html">ORC Extension</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/parquet.html">Apache Parquet Extension</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/postgresql.html">PostgreSQL Metadata Store</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/protobuf.html">Protobuf</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/s3.html">S3-compatible</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/simple-client-sslcontext.html">Simple SSLContext Provider Module</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/stats.html">Stats aggregator</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-core/test-stats.html">Test Stats Aggregators</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/ambari-metrics-emitter.html">Ambari Metrics Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/azure.html">Microsoft Azure</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/cassandra.html">Apache Cassandra</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/cloudfiles.html">Rackspace Cloud Files</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/distinctcount.html">DistinctCount Aggregator</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/graphite.html">Graphite Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/aggregations.html">Aggregations</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/datasource.html">Datasources</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/dimensionspecs.html">Transforming Dimension Values</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/filters.html">Query Filters</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/granularities.html">Aggregation Granularity</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/having.html">Filter groupBy query results</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/hll-old.html">Cardinality/HyperUnique aggregators</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/limitspec.html">Sort groupBy query results</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/post-aggregations.html">Post-Aggregations</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/query-context.html">Query context</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/searchqueryspec.html">Refining search queries</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/sorting-orders.html">Sorting Orders</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/topnmetricspec.html">TopNMetricSpec</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/virtual-columns.html">Virtual Columns</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/influx.html">InfluxDB Line Protocol Parser</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/influxdb-emitter.html">InfluxDB Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/kafka-emitter.html">Kafka Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/materialized-view.html">Materialized View</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/momentsketch-quantiles.html">Moment Sketches for Approximate Quantiles module</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/moving-average-query.html">development/extensions-contrib/moving-average-query</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/opentsdb-emitter.html">OpenTSDB Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/redis-cache.html">Druid Redis Cache</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/sqlserver.html">Microsoft SQLServer</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/statsd.html">StatsD Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/tdigestsketch-quantiles.html">T-Digest Quantiles Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/thrift.html">Thrift</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/time-min-max.html">Timestamp Min/Max aggregators</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/ingestion/standalone-realtime.html">Realtime Process</a></li></ul></div></div></section></div><script>
var coll = document.getElementsByClassName('collapsible');
var checkActiveCategory = true;
for (var i = 0; i < coll.length; i++) {
var links = coll[i].nextElementSibling.getElementsByTagName('*');
if (checkActiveCategory){
for (var j = 0; j < links.length; j++) {
if (links[j].classList.contains('navListItemActive')){
coll[i].nextElementSibling.classList.toggle('hide');
coll[i].childNodes[1].classList.toggle('rotate');
checkActiveCategory = false;
break;
}
}
}
coll[i].addEventListener('click', function() {
var arrow = this.childNodes[1];
arrow.classList.toggle('rotate');
var content = this.nextElementSibling;
content.classList.toggle('hide');
});
}
document.addEventListener('DOMContentLoaded', function() {
createToggler('#navToggler', '#docsNav', 'docsSliderActive');
createToggler('#tocToggler', 'body', 'tocActive');
var headings = document.querySelector('.toc-headings');
headings && headings.addEventListener('click', function(event) {
var el = event.target;
while(el !== headings){
if (el.tagName === 'A') {
document.body.classList.remove('tocActive');
break;
} else{
el = el.parentNode;
}
}
}, false);
function createToggler(togglerSelector, targetSelector, className) {
var toggler = document.querySelector(togglerSelector);
var target = document.querySelector(targetSelector);
if (!toggler) {
return;
}
toggler.onclick = function(event) {
event.preventDefault();
target.classList.toggle(className);
};
}
});
</script></nav></div><div class="container mainContainer"><div class="wrapper"><div class="post"><header class="postHeader"><a class="edit-page-link button" href="https://github.com/apache/druid/edit/master/docs/development/extensions-core/approximate-histograms.md" target="_blank" rel="noreferrer noopener">Edit</a><h1 class="postHeaderTitle">Approximate Histogram aggregators</h1></header><article><div><span><!--
~ Licensed to the Apache Software Foundation (ASF) under one
~ or more contributor license agreements. See the NOTICE file
~ distributed with this work for additional information
~ regarding copyright ownership. The ASF licenses this file
~ to you under the Apache License, Version 2.0 (the
~ "License"); you may not use this file except in compliance
~ with the License. You may obtain a copy of the License at
~
~ http://www.apache.org/licenses/LICENSE-2.0
~
~ Unless required by applicable law or agreed to in writing,
~ software distributed under the License is distributed on an
~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
~ KIND, either express or implied. See the License for the
~ specific language governing permissions and limitations
~ under the License.
-->
<p>To use this Apache Druid extension, make sure to <a href="/docs/latest/development/extensions.html#loading-extensions">include</a> <code>druid-histogram</code> as an extension.</p>
<p>The <code>druid-histogram</code> extension provides an approximate histogram aggregator and a fixed buckets histogram aggregator.</p>
<p><a name="approximate-histogram-aggregator"></a></p>
<h2><a class="anchor" aria-hidden="true" id="approximate-histogram-aggregator-deprecated"></a><a href="#approximate-histogram-aggregator-deprecated" 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>Approximate Histogram aggregator (Deprecated)</h2>
<blockquote>
<p>The Approximate Histogram aggregator is deprecated. Please use <a href="/docs/latest/development/extensions-core/datasketches-quantiles.html">DataSketches Quantiles</a> instead which provides a superior distribution-independent algorithm with formal error guarantees.</p>
</blockquote>
<p>This aggregator is based on
<a href="http://jmlr.org/papers/volume11/ben-haim10a/ben-haim10a.pdf">http://jmlr.org/papers/volume11/ben-haim10a/ben-haim10a.pdf</a>
to compute approximate histograms, with the following modifications:</p>
<ul>
<li>some tradeoffs in accuracy were made in the interest of speed (see below)</li>
<li>the sketch maintains the exact original data as long as the number of
distinct data points is fewer than the resolutions (number of centroids),
increasing accuracy when there are few data points, or when dealing with
discrete data points. You can find some of the details in <a href="https://metamarkets.com/2013/histograms/">this post</a>.</li>
</ul>
<p>Approximate histogram sketches are still experimental for a reason, and you
should understand the limitations of the current implementation before using
them. The approximation is heavily data-dependent, which makes it difficult to
give good general guidelines, so you should experiment and see what parameters
work well for your data.</p>
<p>Here are a few things to note before using them:</p>
<ul>
<li>As indicated in the original paper, there are no formal error bounds on the
approximation. In practice, the approximation gets worse if the distribution
is skewed.</li>
<li>The algorithm is order-dependent, so results can vary for the same query, due
to variations in the order in which results are merged.</li>
<li>In general, the algorithm only works well if the data that comes is randomly
distributed (i.e. if data points end up sorted in a column, approximation
will be horrible)</li>
<li>We traded accuracy for aggregation speed, taking some shortcuts when adding
histograms together, which can lead to pathological cases if your data is
ordered in some way, or if your distribution has long tails. It should be
cheaper to increase the resolution of the sketch to get the accuracy you need.</li>
</ul>
<p>That being said, those sketches can be useful to get a first order approximation
when averages are not good enough. Assuming most rows in your segment store
fewer data points than the resolution of histogram, you should be able to use
them for monitoring purposes and detect meaningful variations with a few
hundred centroids. To get good accuracy readings on 95th percentiles with
millions of rows of data, you may want to use several thousand centroids,
especially with long tails, since that's where the approximation will be worse.</p>
<h3><a class="anchor" aria-hidden="true" id="creating-approximate-histogram-sketches-at-ingestion-time"></a><a href="#creating-approximate-histogram-sketches-at-ingestion-time" 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>Creating approximate histogram sketches at ingestion time</h3>
<p>To use this feature, an &quot;approxHistogram&quot; or &quot;approxHistogramFold&quot; aggregator must be included at
indexing time. The ingestion aggregator can only apply to numeric values. If you use &quot;approxHistogram&quot;
then any input rows missing the value will be considered to have a value of 0, while with &quot;approxHistogramFold&quot;
such rows will be ignored.</p>
<p>To query for results, an &quot;approxHistogramFold&quot; aggregator must be included in the
query.</p>
<pre><code class="hljs css language-json">{
<span class="hljs-attr">"type"</span> : <span class="hljs-string">"approxHistogram or approxHistogramFold (at ingestion time), approxHistogramFold (at query time)"</span>,
<span class="hljs-attr">"name"</span> : &lt;output_name&gt;,
<span class="hljs-attr">"fieldName"</span> : &lt;metric_name&gt;,
<span class="hljs-attr">"resolution"</span> : &lt;integer&gt;,
<span class="hljs-attr">"numBuckets"</span> : &lt;integer&gt;,
<span class="hljs-attr">"lowerLimit"</span> : &lt;float&gt;,
<span class="hljs-attr">"upperLimit"</span> : &lt;float&gt;
}
</code></pre>
<table>
<thead>
<tr><th>Property</th><th>Description</th><th>Default</th></tr>
</thead>
<tbody>
<tr><td><code>resolution</code></td><td>Number of centroids (data points) to store. The higher the resolution, the more accurate results are, but the slower the computation will be.</td><td>50</td></tr>
<tr><td><code>numBuckets</code></td><td>Number of output buckets for the resulting histogram. Bucket intervals are dynamic, based on the range of the underlying data. Use a post-aggregator to have finer control over the bucketing scheme</td><td>7</td></tr>
<tr><td><code>lowerLimit</code>/<code>upperLimit</code></td><td>Restrict the approximation to the given range. The values outside this range will be aggregated into two centroids. Counts of values outside this range are still maintained.</td><td>-INF/+INF</td></tr>
<tr><td><code>finalizeAsBase64Binary</code></td><td>If true, the finalized aggregator value will be a Base64-encoded byte array containing the serialized form of the histogram. If false, the finalized aggregator value will be a JSON representation of the histogram.</td><td>false</td></tr>
</tbody>
</table>
<h2><a class="anchor" aria-hidden="true" id="fixed-buckets-histogram"></a><a href="#fixed-buckets-histogram" 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>Fixed Buckets Histogram</h2>
<p>The fixed buckets histogram aggregator builds a histogram on a numeric column, with evenly-sized buckets across a specified value range. Values outside of the range are handled based on a user-specified outlier handling mode.</p>
<p>This histogram supports the min/max/quantiles post-aggregators but does not support the bucketing post-aggregators.</p>
<h3><a class="anchor" aria-hidden="true" id="when-to-use"></a><a href="#when-to-use" 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>When to use</h3>
<p>The accuracy/usefulness of the fixed buckets histogram is extremely data-dependent; it is provided to support special use cases where the user has a great deal of prior information about the data being aggregated and knows that a fixed buckets implementation is suitable.</p>
<p>For general histogram and quantile use cases, the <a href="/docs/latest/development/extensions-core/datasketches-quantiles.html">DataSketches Quantiles Sketch</a> extension is recommended.</p>
<h3><a class="anchor" aria-hidden="true" id="properties"></a><a href="#properties" 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>Properties</h3>
<table>
<thead>
<tr><th>Property</th><th>Description</th><th>Default</th></tr>
</thead>
<tbody>
<tr><td><code>type</code></td><td>Type of the aggregator. Must <code>fixedBucketsHistogram</code>.</td><td>No default, must be specified</td></tr>
<tr><td><code>name</code></td><td>Column name for the aggregator.</td><td>No default, must be specified</td></tr>
<tr><td><code>fieldName</code></td><td>Column name of the input to the aggregator.</td><td>No default, must be specified</td></tr>
<tr><td><code>lowerLimit</code></td><td>Lower limit of the histogram.</td><td>No default, must be specified</td></tr>
<tr><td><code>upperLimit</code></td><td>Upper limit of the histogram.</td><td>No default, must be specified</td></tr>
<tr><td><code>numBuckets</code></td><td>Number of buckets for the histogram. The range [lowerLimit, upperLimit] will be divided into <code>numBuckets</code> intervals of equal size.</td><td>10</td></tr>
<tr><td><code>outlierHandlingMode</code></td><td>Specifies how values outside of [lowerLimit, upperLimit] will be handled. Supported modes are &quot;ignore&quot;, &quot;overflow&quot;, and &quot;clip&quot;. See <a href="#outlier-handling-modes">outlier handling modes</a> for more details.</td><td>No default, must be specified</td></tr>
<tr><td><code>finalizeAsBase64Binary</code></td><td>If true, the finalized aggregator value will be a Base64-encoded byte array containing the <a href="#serialization-formats">serialized form</a> of the histogram. If false, the finalized aggregator value will be a JSON representation of the histogram.</td><td>false</td></tr>
</tbody>
</table>
<p>An example aggregator spec is shown below:</p>
<pre><code class="hljs css language-json">{
<span class="hljs-attr">"type"</span> : <span class="hljs-string">"fixedBucketsHistogram"</span>,
<span class="hljs-attr">"name"</span> : &lt;output_name&gt;,
<span class="hljs-attr">"fieldName"</span> : &lt;metric_name&gt;,
<span class="hljs-attr">"numBuckets"</span> : &lt;integer&gt;,
<span class="hljs-attr">"lowerLimit"</span> : &lt;double&gt;,
<span class="hljs-attr">"upperLimit"</span> : &lt;double&gt;,
<span class="hljs-attr">"outlierHandlingMode"</span>: &lt;mode&gt;
}
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="outlier-handling-modes"></a><a href="#outlier-handling-modes" 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>Outlier handling modes</h3>
<p>The outlier handling mode specifies what should be done with values outside of the histogram's range. There are three supported modes:</p>
<ul>
<li><code>ignore</code>: Throw away outlier values.</li>
<li><code>overflow</code>: A count of outlier values will be tracked by the histogram, available in the <code>lowerOutlierCount</code> and <code>upperOutlierCount</code> fields.</li>
<li><code>clip</code>: Outlier values will be clipped to the <code>lowerLimit</code> or the <code>upperLimit</code> and included in the histogram.</li>
</ul>
<p>If you don't care about outliers, <code>ignore</code> is the cheapest option performance-wise. There is currently no difference in storage size among the modes.</p>
<h3><a class="anchor" aria-hidden="true" id="output-fields"></a><a href="#output-fields" 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>Output fields</h3>
<p>The histogram aggregator's output object has the following fields:</p>
<ul>
<li><code>lowerLimit</code>: Lower limit of the histogram</li>
<li><code>upperLimit</code>: Upper limit of the histogram</li>
<li><code>numBuckets</code>: Number of histogram buckets</li>
<li><code>outlierHandlingMode</code>: Outlier handling mode</li>
<li><code>count</code>: Total number of values contained in the histogram, excluding outliers</li>
<li><code>lowerOutlierCount</code>: Count of outlier values below <code>lowerLimit</code>. Only used if the outlier mode is <code>overflow</code>.</li>
<li><code>upperOutlierCount</code>: Count of outlier values above <code>upperLimit</code>. Only used if the outlier mode is <code>overflow</code>.</li>
<li><code>missingValueCount</code>: Count of null values seen by the histogram.</li>
<li><code>max</code>: Max value seen by the histogram. This does not include outlier values.</li>
<li><code>min</code>: Min value seen by the histogram. This does not include outlier values.</li>
<li><code>histogram</code>: An array of longs with size <code>numBuckets</code>, containing the bucket counts</li>
</ul>
<h3><a class="anchor" aria-hidden="true" id="ingesting-existing-histograms"></a><a href="#ingesting-existing-histograms" 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>Ingesting existing histograms</h3>
<p>It is also possible to ingest existing fixed buckets histograms. The input must be a Base64 string encoding a byte array that contains a serialized histogram object. Both &quot;full&quot; and &quot;sparse&quot; formats can be used. Please see <a href="#serialization-formats">Serialization formats</a> below for details.</p>
<h3><a class="anchor" aria-hidden="true" id="serialization-formats"></a><a href="#serialization-formats" 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>Serialization formats</h3>
<h4><a class="anchor" aria-hidden="true" id="full-serialization-format"></a><a href="#full-serialization-format" 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>Full serialization format</h4>
<p>This format includes the full histogram bucket count array in the serialization format.</p>
<pre><code class="hljs"><span class="hljs-keyword">byte</span>: serialization version, must be <span class="hljs-number">0x01</span>
<span class="hljs-keyword">byte</span>: encoding mode, <span class="hljs-number">0x01</span> <span class="hljs-built_in">for</span> full
<span class="hljs-keyword">double</span>: lowerLimit
<span class="hljs-keyword">double</span>: upperLimit
<span class="hljs-keyword">int</span>: numBuckets
<span class="hljs-keyword">byte</span>: outlier handling mode (<span class="hljs-number">0x00</span> <span class="hljs-built_in">for</span> `ignore`, <span class="hljs-number">0x01</span> <span class="hljs-built_in">for</span> `<span class="hljs-built_in">overflow</span>`, <span class="hljs-keyword">and</span> <span class="hljs-number">0x02</span> <span class="hljs-built_in">for</span> `clip`)
<span class="hljs-keyword">long</span>: count, total number of values contained in the histogram, excluding outliers
<span class="hljs-keyword">long</span>: lowerOutlierCount
<span class="hljs-keyword">long</span>: upperOutlierCount
<span class="hljs-keyword">long</span>: missingValueCount
<span class="hljs-keyword">double</span>: <span class="hljs-built_in">max</span>
<span class="hljs-keyword">double</span>: <span class="hljs-built_in">min</span>
<span class="hljs-keyword">array</span> of longs: bucket counts <span class="hljs-built_in">for</span> the histogram
</code></pre>
<h4><a class="anchor" aria-hidden="true" id="sparse-serialization-format"></a><a href="#sparse-serialization-format" 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>Sparse serialization format</h4>
<p>This format represents the histogram bucket counts as (bucketNum, count) pairs. This serialization format is used when less than half of the histogram's buckets have values.</p>
<pre><code class="hljs">byte: serialization <span class="hljs-keyword">version</span>, must <span class="hljs-keyword">be</span> <span class="hljs-number">0</span>x01
byte: encoding <span class="hljs-keyword">mode</span>, <span class="hljs-number">0</span>x02 <span class="hljs-keyword">for</span> sparse
double: lowerLimit
double: upperLimit
in<span class="hljs-variable">t:</span> numBuckets
byte: outlier handling <span class="hljs-keyword">mode</span> (<span class="hljs-number">0</span>x00 <span class="hljs-keyword">for</span> `ignore`, <span class="hljs-number">0</span>x01 <span class="hljs-keyword">for</span> `overflow`, <span class="hljs-built_in">and</span> <span class="hljs-number">0</span>x02 <span class="hljs-keyword">for</span> `clip`)
lon<span class="hljs-variable">g:</span> <span class="hljs-built_in">count</span>, total <span class="hljs-keyword">number</span> of <span class="hljs-built_in">values</span> contained in the histogram, excluding outliers
lon<span class="hljs-variable">g:</span> lowerOutlierCount
lon<span class="hljs-variable">g:</span> upperOutlierCount
lon<span class="hljs-variable">g:</span> missingValueCount
double: <span class="hljs-built_in">max</span>
double: <span class="hljs-built_in">min</span>
in<span class="hljs-variable">t:</span> <span class="hljs-keyword">number</span> of following (bucketNum, <span class="hljs-built_in">count</span>) pairs
sequence of (<span class="hljs-keyword">int</span>, long) pair<span class="hljs-variable">s:</span>
in<span class="hljs-variable">t:</span> bucket <span class="hljs-keyword">number</span>
coun<span class="hljs-variable">t:</span> bucket <span class="hljs-built_in">count</span>
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="combining-histograms-with-different-bucketing-schemes"></a><a href="#combining-histograms-with-different-bucketing-schemes" 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>Combining histograms with different bucketing schemes</h3>
<p>It is possible to combine two histograms with different bucketing schemes (lowerLimit, upperLimit, numBuckets) together.</p>
<p>The bucketing scheme of the &quot;left hand&quot; histogram will be preserved (i.e., when running a query, the bucketing schemes specified in the query's histogram aggregators will be preserved).</p>
<p>When merging, we assume that values are evenly distributed within the buckets of the &quot;right hand&quot; histogram.</p>
<p>When the right-hand histogram contains outliers (when using <code>overflow</code> mode), we assume that all of the outliers counted in the right-hand histogram will be outliers in the left-hand histogram as well.</p>
<p>For performance and accuracy reasons, we recommend avoiding aggregation of histograms with different bucketing schemes if possible.</p>
<h3><a class="anchor" aria-hidden="true" id="null-handling"></a><a href="#null-handling" 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>Null handling</h3>
<p>If <code>druid.generic.useDefaultValueForNull</code> is false, null values will be tracked in the <code>missingValueCount</code> field of the histogram.</p>
<p>If <code>druid.generic.useDefaultValueForNull</code> is true, null values will be added to the histogram as the default 0.0 value.</p>
<h2><a class="anchor" aria-hidden="true" id="histogram-post-aggregators"></a><a href="#histogram-post-aggregators" 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>Histogram post-aggregators</h2>
<p>Post-aggregators are used to transform opaque approximate histogram sketches
into bucketed histogram representations, as well as to compute various
distribution metrics such as quantiles, min, and max.</p>
<h3><a class="anchor" aria-hidden="true" id="equal-buckets-post-aggregator"></a><a href="#equal-buckets-post-aggregator" 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>Equal buckets post-aggregator</h3>
<p>Computes a visual representation of the approximate histogram with a given number of equal-sized bins.
Bucket intervals are based on the range of the underlying data. This aggregator is not supported for the fixed buckets histogram.</p>
<pre><code class="hljs css language-json">{
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"equalBuckets"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"&lt;output_name&gt;"</span>,
<span class="hljs-attr">"fieldName"</span>: <span class="hljs-string">"&lt;aggregator_name&gt;"</span>,
<span class="hljs-attr">"numBuckets"</span>: &lt;count&gt;
}
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="buckets-post-aggregator"></a><a href="#buckets-post-aggregator" 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>Buckets post-aggregator</h3>
<p>Computes a visual representation given an initial breakpoint, offset, and a bucket size.</p>
<p>Bucket size determines the width of the binning interval.</p>
<p>Offset determines the value on which those interval bins align.</p>
<p>This aggregator is not supported for the fixed buckets histogram.</p>
<pre><code class="hljs css language-json">{
<span class="hljs-attr">"type"</span>: <span class="hljs-string">"buckets"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"&lt;output_name&gt;"</span>,
<span class="hljs-attr">"fieldName"</span>: <span class="hljs-string">"&lt;aggregator_name&gt;"</span>,
<span class="hljs-attr">"bucketSize"</span>: &lt;bucket_size&gt;,
<span class="hljs-attr">"offset"</span>: &lt;offset&gt;
}
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="custom-buckets-post-aggregator"></a><a href="#custom-buckets-post-aggregator" 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>Custom buckets post-aggregator</h3>
<p>Computes a visual representation of the approximate histogram with bins laid out according to the given breaks.</p>
<p>This aggregator is not supported for the fixed buckets histogram.</p>
<pre><code class="hljs css language-json">{ <span class="hljs-attr">"type"</span> : <span class="hljs-string">"customBuckets"</span>, <span class="hljs-attr">"name"</span> : &lt;output_name&gt;, <span class="hljs-attr">"fieldName"</span> : &lt;aggregator_name&gt;,
<span class="hljs-attr">"breaks"</span> : [ &lt;value&gt;, &lt;value&gt;, ... ] }
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="min-post-aggregator"></a><a href="#min-post-aggregator" 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>min post-aggregator</h3>
<p>Returns the minimum value of the underlying approximate or fixed buckets histogram aggregator</p>
<pre><code class="hljs css language-json">{ <span class="hljs-attr">"type"</span> : <span class="hljs-string">"min"</span>, <span class="hljs-attr">"name"</span> : &lt;output_name&gt;, <span class="hljs-attr">"fieldName"</span> : &lt;aggregator_name&gt; }
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="max-post-aggregator"></a><a href="#max-post-aggregator" 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>max post-aggregator</h3>
<p>Returns the maximum value of the underlying approximate or fixed buckets histogram aggregator</p>
<pre><code class="hljs css language-json">{ <span class="hljs-attr">"type"</span> : <span class="hljs-string">"max"</span>, <span class="hljs-attr">"name"</span> : &lt;output_name&gt;, <span class="hljs-attr">"fieldName"</span> : &lt;aggregator_name&gt; }
</code></pre>
<h4><a class="anchor" aria-hidden="true" id="quantile-post-aggregator"></a><a href="#quantile-post-aggregator" 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>quantile post-aggregator</h4>
<p>Computes a single quantile based on the underlying approximate or fixed buckets histogram aggregator</p>
<pre><code class="hljs css language-json">{ <span class="hljs-attr">"type"</span> : <span class="hljs-string">"quantile"</span>, <span class="hljs-attr">"name"</span> : &lt;output_name&gt;, <span class="hljs-attr">"fieldName"</span> : &lt;aggregator_name&gt;,
<span class="hljs-attr">"probability"</span> : &lt;quantile&gt; }
</code></pre>
<h4><a class="anchor" aria-hidden="true" id="quantiles-post-aggregator"></a><a href="#quantiles-post-aggregator" 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>quantiles post-aggregator</h4>
<p>Computes an array of quantiles based on the underlying approximate or fixed buckets histogram aggregator</p>
<pre><code class="hljs css language-json">{ <span class="hljs-attr">"type"</span> : <span class="hljs-string">"quantiles"</span>, <span class="hljs-attr">"name"</span> : &lt;output_name&gt;, <span class="hljs-attr">"fieldName"</span> : &lt;aggregator_name&gt;,
<span class="hljs-attr">"probabilities"</span> : [ &lt;quantile&gt;, &lt;quantile&gt;, ... ] }
</code></pre>
</span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/latest/design/peons.html"><span class="arrow-prev">← </span><span>Peons</span></a><a class="docs-next button" href="/docs/latest/development/extensions-core/avro.html"><span>Apache Avro</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#approximate-histogram-aggregator-deprecated">Approximate Histogram aggregator (Deprecated)</a><ul class="toc-headings"><li><a href="#creating-approximate-histogram-sketches-at-ingestion-time">Creating approximate histogram sketches at ingestion time</a></li></ul></li><li><a href="#fixed-buckets-histogram">Fixed Buckets Histogram</a><ul class="toc-headings"><li><a href="#when-to-use">When to use</a></li><li><a href="#properties">Properties</a></li><li><a href="#outlier-handling-modes">Outlier handling modes</a></li><li><a href="#output-fields">Output fields</a></li><li><a href="#ingesting-existing-histograms">Ingesting existing histograms</a></li><li><a href="#serialization-formats">Serialization formats</a></li><li><a href="#combining-histograms-with-different-bucketing-schemes">Combining histograms with different bucketing schemes</a></li><li><a href="#null-handling">Null handling</a></li></ul></li><li><a href="#histogram-post-aggregators">Histogram post-aggregators</a><ul class="toc-headings"><li><a href="#equal-buckets-post-aggregator">Equal buckets post-aggregator</a></li><li><a href="#buckets-post-aggregator">Buckets post-aggregator</a></li><li><a href="#custom-buckets-post-aggregator">Custom buckets post-aggregator</a></li><li><a href="#min-post-aggregator">min post-aggregator</a></li><li><a href="#max-post-aggregator">max post-aggregator</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/latest/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/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>
document.addEventListener('keyup', function(e) {
if (e.target !== document.body) {
return;
}
// keyCode for '/' (slash)
if (e.keyCode === 191) {
const search = document.getElementById('search_input_react');
search && search.focus();
}
});
</script><script>
var search = docsearch({
apiKey: '2de99082a9f38e49dfaa059bbe4c901d',
indexName: 'apache_druid',
inputSelector: '#search_input_react',
algoliaOptions: {"facetFilters":["language:en","version:0.17.1"]}
});
</script></body></html>