| <!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>Apache Kafka Lookups · Apache Druid</title><meta name="viewport" content="width=device-width, initial-scale=1.0"/><link rel="canonical" href="https://druid.apache.org/docs/26.0.0/development/extensions-core/kafka-extraction-namespace.html"/><meta name="generator" content="Docusaurus"/><meta name="description" content="<!--"/><meta name="docsearch:language" content="en"/><meta name="docsearch:version" content="26.0.0" /><meta property="og:title" content="Apache Kafka Lookups · Apache Druid"/><meta property="og:type" content="website"/><meta property="og:url" content="https://druid.apache.org/index.html"/><meta property="og:description" content="<!--"/><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/npm/docsearch.js@2/dist/cdn/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/26.0.0/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/26.0.0/design/index.html">Introduction to Apache Druid</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/index.html">Quickstart (local)</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/single-server.html">Single server deployment</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/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/26.0.0/tutorials/tutorial-batch.html">Load files natively</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-msq-extern.html">Load files using SQL 🆕</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-kafka.html">Load from Apache Kafka</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-batch-hadoop.html">Load from Apache Hadoop</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-query.html">Querying data</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-rollup.html">Roll-up</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-sketches-theta.html">Theta sketches</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-retention.html">Configuring data retention</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-update-data.html">Updating existing data</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-compaction.html">Compacting segments</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-delete-data.html">Deleting data</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-ingestion-spec.html">Writing an ingestion spec</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-transform-spec.html">Transforming input data</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/docker.html">Tutorial: Run with Docker</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-kerberos-hadoop.html">Kerberized HDFS deep storage</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-msq-convert-spec.html">Convert ingestion spec to SQL</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-sql-query-view.html">Get to know Query view</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-unnest-arrays.html">Unnesting arrays</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-jupyter-index.html">Jupyter Notebook tutorials</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-jupyter-docker.html">Docker for tutorials</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/tutorials/tutorial-jdbc.html">JDBC connector</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/26.0.0/design/architecture.html">Design</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/segments.html">Segments</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/processes.html">Processes and servers</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/dependencies/deep-storage.html">Deep storage</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/dependencies/metadata-storage.html">Metadata storage</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/dependencies/zookeeper.html">ZooKeeper</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">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/26.0.0/ingestion/index.html">Ingestion</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/data-formats.html">Data formats</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/data-model.html">Data model</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/rollup.html">Data rollup</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/partitioning.html">Partitioning</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/ingestion-spec.html">Ingestion spec</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/schema-design.html">Schema design tips</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Stream ingestion</h4><ul><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/kafka-ingestion.html">Apache Kafka ingestion</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/kafka-supervisor-reference.html">Apache Kafka supervisor</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/kafka-supervisor-operations.html">Apache Kafka operations</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/kinesis-ingestion.html">Amazon Kinesis</a></li></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Batch ingestion</h4><ul><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/native-batch.html">Native batch</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/native-batch-input-sources.html">Native batch: input sources</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/migrate-from-firehose.html">Migrate from firehose</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/hadoop.html">Hadoop-based</a></li></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">SQL-based ingestion 🆕</h4><ul><li class="navListItem"><a class="navItem" href="/docs/26.0.0/multi-stage-query/index.html">Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/multi-stage-query/concepts.html">Key concepts</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/multi-stage-query/api.html">API</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/multi-stage-query/security.html">Security</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/multi-stage-query/examples.html">Examples</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/multi-stage-query/reference.html">Reference</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/multi-stage-query/known-issues.html">Known issues</a></li></ul></div><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/tasks.html">Task reference</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/faq.html">Troubleshooting FAQ</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle collapsible">Data management<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/26.0.0/data-management/index.html">Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/data-management/update.html">Data updates</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/data-management/delete.html">Data deletion</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/data-management/schema-changes.html">Schema changes</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/data-management/compaction.html">Compaction</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/data-management/automatic-compaction.html">Automatic compaction</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"><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Druid SQL</h4><ul><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql.html">Overview and syntax</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-data-types.html">SQL data types</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-operators.html">Operators</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-scalar.html">Scalar functions</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-aggregations.html">Aggregation functions</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-multivalue-string-functions.html">Multi-value string functions</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-json-functions.html">JSON functions</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-functions.html">All functions</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-api.html">Druid SQL API</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-jdbc.html">JDBC driver API</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-query-context.html">SQL query context</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-metadata-tables.html">SQL metadata tables</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sql-translation.html">SQL query translation</a></li></ul></div><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/querying.html">Native queries</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/query-execution.html">Query execution</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/troubleshooting.html">Troubleshooting</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Concepts</h4><ul><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/datasource.html">Datasources</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/joins.html">Joins</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/lookups.html">Lookups</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/multi-value-dimensions.html">Multi-value dimensions</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/nested-columns.html">Nested columns</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/multitenancy.html">Multitenancy</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/caching.html">Query caching</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/using-caching.html">Using query caching</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/query-context.html">Query context</a></li></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Native query types</h4><ul><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/timeseriesquery.html">Timeseries</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/topnquery.html">TopN</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/groupbyquery.html">GroupBy</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/scan-query.html">Scan</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/searchquery.html">Search</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/timeboundaryquery.html">TimeBoundary</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/segmentmetadataquery.html">SegmentMetadata</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/datasourcemetadataquery.html">DatasourceMetadata</a></li></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Native query components</h4><ul><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/filters.html">Filters</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/granularities.html">Granularities</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/dimensionspecs.html">Dimensions</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/aggregations.html">Aggregations</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/post-aggregations.html">Post-aggregations</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/misc/math-expr.html">Expressions</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/having.html">Having filters (groupBy)</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/limitspec.html">Sorting and limiting (groupBy)</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/topnmetricspec.html">Sorting (topN)</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/sorting-orders.html">String comparators</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/virtual-columns.html">Virtual columns</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/geo.html">Spatial filters</a></li></ul></div></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/26.0.0/configuration/index.html">Configuration reference</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions.html">Extensions</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/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/26.0.0/operations/web-console.html">Web console</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/java.html">Java runtime</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Security</h4><ul><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/security-overview.html">Security overview</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/security-user-auth.html">User authentication and authorization</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/auth-ldap.html">LDAP auth</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/password-provider.html">Password providers</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/dynamic-config-provider.html">Dynamic Config Providers</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/tls-support.html">TLS support</a></li></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Performance tuning</h4><ul><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/basic-cluster-tuning.html">Basic cluster tuning</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/segment-optimization.html">Segment size optimization</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/mixed-workloads.html">Mixed workloads</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/http-compression.html">HTTP compression</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/clean-metadata-store.html">Automated metadata cleanup</a></li></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Monitoring</h4><ul><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/request-logging.html">Request logging</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/metrics.html">Metrics</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/alerts.html">Alerts</a></li></ul></div><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/api-reference.html">API reference</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/high-availability.html">High availability</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/rolling-updates.html">Rolling updates</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/rule-configuration.html">Using rules to drop and retain data</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/other-hadoop.html">Working with different versions of Apache Hadoop</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Misc</h4><ul><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/dump-segment.html">dump-segment tool</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/reset-cluster.html">reset-cluster tool</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/insert-segment-to-db.html">insert-segment-to-db tool</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/pull-deps.html">pull-deps tool</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/deep-storage-migration.html">Deep storage migration</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/export-metadata.html">Export Metadata Tool</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/metadata-migration.html">Metadata Migration</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/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/26.0.0/development/overview.html">Developing on Druid</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/modules.html">Creating extensions</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/javascript.html">JavaScript functionality</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/build.html">Build from source</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/versioning.html">Versioning</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/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/26.0.0/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/26.0.0/comparisons/druid-vs-elasticsearch.html">Apache Druid vs Elasticsearch</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/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/26.0.0/comparisons/druid-vs-kudu.html">Apache Druid vs Kudu</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/comparisons/druid-vs-redshift.html">Apache Druid vs Redshift</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/comparisons/druid-vs-spark.html">Apache Druid vs Spark</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/comparisons/druid-vs-sql-on-hadoop.html">Apache Druid vs SQL-on-Hadoop</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/auth.html">Authentication and Authorization</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/broker.html">Broker</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/coordinator.html">Coordinator Process</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/historical.html">Historical Process</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/indexer.html">Indexer Process</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/indexing-service.html">Indexing Service</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/middlemanager.html">MiddleManager Process</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/overlord.html">Overlord Process</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/router.html">Router Process</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/design/peons.html">Peons</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/approximate-histograms.html">Approximate Histogram aggregators</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/avro.html">Apache Avro</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/azure.html">Microsoft Azure</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/bloom-filter.html">Bloom Filter</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/datasketches-extension.html">DataSketches extension</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/datasketches-hll.html">DataSketches HLL Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/datasketches-quantiles.html">DataSketches Quantiles Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/datasketches-theta.html">DataSketches Theta Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/datasketches-tuple.html">DataSketches Tuple Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/druid-basic-security.html">Basic Security</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/druid-kerberos.html">Kerberos</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/druid-lookups.html">Cached Lookup Module</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/druid-ranger-security.html">Apache Ranger Security</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/google.html">Google Cloud Storage</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/hdfs.html">HDFS</a></li><li class="navListItem navListItemActive"><a class="navItem" href="/docs/26.0.0/development/extensions-core/kafka-extraction-namespace.html">Apache Kafka Lookups</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/lookups-cached-global.html">Globally Cached Lookups</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/mysql.html">MySQL Metadata Store</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/orc.html">ORC Extension</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/druid-pac4j.html">Druid pac4j based Security extension</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/parquet.html">Apache Parquet Extension</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/postgresql.html">PostgreSQL Metadata Store</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/protobuf.html">Protobuf</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/s3.html">S3-compatible</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/simple-client-sslcontext.html">Simple SSLContext Provider Module</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/stats.html">Stats aggregator</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/test-stats.html">Test Stats Aggregators</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/druid-aws-rds.html">Druid AWS RDS Module</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-core/kubernetes.html">Kubernetes</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/ambari-metrics-emitter.html">Ambari Metrics Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/cassandra.html">Apache Cassandra</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/cloudfiles.html">Rackspace Cloud Files</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/distinctcount.html">DistinctCount Aggregator</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/graphite.html">Graphite Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/influx.html">InfluxDB Line Protocol Parser</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/influxdb-emitter.html">InfluxDB Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/kafka-emitter.html">Kafka Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/materialized-view.html">Materialized View</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/momentsketch-quantiles.html">Moment Sketches for Approximate Quantiles module</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/moving-average-query.html">Moving Average Query</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/opentsdb-emitter.html">OpenTSDB Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/redis-cache.html">Druid Redis Cache</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/sqlserver.html">Microsoft SQLServer</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/statsd.html">StatsD Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/tdigestsketch-quantiles.html">T-Digest Quantiles Sketch module</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/thrift.html">Thrift</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/time-min-max.html">Timestamp Min/Max aggregators</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/gce-extensions.html">GCE Extensions</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/aliyun-oss.html">Aliyun OSS</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/development/extensions-contrib/prometheus.html">Prometheus Emitter</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/operations/kubernetes.html">kubernetes</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/hll-old.html">Cardinality/HyperUnique aggregators</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/querying/select-query.html">Select</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/native-batch-firehose.html">Firehose (deprecated)</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/ingestion/native-batch-simple-task.html">Native batch (simple)</a></li><li class="navListItem"><a class="navItem" href="/docs/26.0.0/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 docsContainer"><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/kafka-extraction-namespace.md" target="_blank" rel="noreferrer noopener">Edit</a><h1 id="__docusaurus" class="postHeaderTitle">Apache Kafka Lookups</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, <a href="/docs/26.0.0/development/extensions.html#loading-extensions">include</a> <code>druid-lookups-cached-global</code> and <code>druid-kafka-extraction-namespace</code> in the extensions load list.</p> |
| <p>If you need updates to populate as promptly as possible, it is possible to plug into a Kafka topic whose key is the old value and message is the desired new value (both in UTF-8) as a LookupExtractorFactory.</p> |
| <pre><code class="hljs css language-json">{ |
| <span class="hljs-attr">"type"</span>:<span class="hljs-string">"kafka"</span>, |
| <span class="hljs-attr">"kafkaTopic"</span>:<span class="hljs-string">"testTopic"</span>, |
| <span class="hljs-attr">"kafkaProperties"</span>:{ |
| <span class="hljs-attr">"bootstrap.servers"</span>:<span class="hljs-string">"kafka.service:9092"</span> |
| } |
| } |
| </code></pre> |
| <table> |
| <thead> |
| <tr><th>Parameter</th><th>Description</th><th>Required</th><th>Default</th></tr> |
| </thead> |
| <tbody> |
| <tr><td><code>kafkaTopic</code></td><td>The Kafka topic to read the data from</td><td>Yes</td><td></td></tr> |
| <tr><td><code>kafkaProperties</code></td><td>Kafka consumer properties (<code>bootstrap.servers</code> must be specified)</td><td>Yes</td><td></td></tr> |
| <tr><td><code>connectTimeout</code></td><td>How long to wait for an initial connection</td><td>No</td><td><code>0</code> (do not wait)</td></tr> |
| <tr><td><code>isOneToOne</code></td><td>The map is a one-to-one (see <a href="/docs/26.0.0/querying/dimensionspecs.html">Lookup DimensionSpecs</a>)</td><td>No</td><td><code>false</code></td></tr> |
| </tbody> |
| </table> |
| <p>The extension <code>kafka-extraction-namespace</code> enables reading from an <a href="https://kafka.apache.org/">Apache Kafka</a> topic which has name/key pairs to allow renaming of dimension values. An example use case would be to rename an ID to a human-readable format.</p> |
| <h2><a class="anchor" aria-hidden="true" id="how-it-works"></a><a href="#how-it-works" 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>How it Works</h2> |
| <p>The extractor works by consuming the configured Kafka topic from the beginning, and appending every record to an internal map. The key of the Kafka record is used as they key of the map, and the payload of the record is used as the value. At query time, a lookup can be used to transform the key into the associated value. See <a href="/docs/26.0.0/querying/lookups.html">lookups</a> for how to configure and use lookups in a query. Keys and values are both stored as strings by the lookup extractor.</p> |
| <p>The extractor remains subscribed to the topic, so new records are added to the lookup map as they appear. This allows for lookup values to be updated in near-realtime. If two records are added to the topic with the same key, the record with the larger offset will replace the previous record in the lookup map. A record with a <code>null</code> payload will be treated as a tombstone record, and the associated key will be removed from the lookup map.</p> |
| <p>The extractor treats the input topic much like a <a href="https://kafka.apache.org/23/javadoc/org/apache/kafka/streams/kstream/KTable.html">KTable</a>. As such, it is best to create your Kafka topic using a <a href="https://kafka.apache.org/documentation/#compaction">log compaction</a> strategy, so that the most-recent version of a key is always preserved in Kafka. Without properly configuring retention and log compaction, older keys that are automatically removed from Kafka will not be available and will be lost when Druid services are restarted.</p> |
| <h3><a class="anchor" aria-hidden="true" id="example"></a><a href="#example" 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>Example</h3> |
| <p>Consider a <code>country_codes</code> topic is being consumed, and the following records are added to the topic in the following order:</p> |
| <table> |
| <thead> |
| <tr><th>Offset</th><th>Key</th><th>Payload</th></tr> |
| </thead> |
| <tbody> |
| <tr><td>1</td><td>NZ</td><td>Nu Zeelund</td></tr> |
| <tr><td>2</td><td>AU</td><td>Australia</td></tr> |
| <tr><td>3</td><td>NZ</td><td>New Zealand</td></tr> |
| <tr><td>4</td><td>AU</td><td><code>null</code></td></tr> |
| <tr><td>5</td><td>NZ</td><td>Aotearoa</td></tr> |
| <tr><td>6</td><td>CZ</td><td>Czechia</td></tr> |
| </tbody> |
| </table> |
| <p>This input topic would be consumed from the beginning, and result in a lookup namespace containing the following mappings (notice that the entry for <em>Australia</em> was added and then deleted):</p> |
| <table> |
| <thead> |
| <tr><th>Key</th><th>Value</th></tr> |
| </thead> |
| <tbody> |
| <tr><td>NZ</td><td>Aotearoa</td></tr> |
| <tr><td>CZ</td><td>Czechia</td></tr> |
| </tbody> |
| </table> |
| <p>Now when a query uses this extraction namespace, the country codes can be mapped to the full country name at query time.</p> |
| <h2><a class="anchor" aria-hidden="true" id="tombstones-and-deleting-records"></a><a href="#tombstones-and-deleting-records" 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>Tombstones and Deleting Records</h2> |
| <p>The Kafka lookup extractor treats <code>null</code> Kafka messages as tombstones. This means that a record on the input topic with a <code>null</code> message payload on Kafka will remove the associated key from the lookup map, effectively deleting it.</p> |
| <h2><a class="anchor" aria-hidden="true" id="limitations"></a><a href="#limitations" 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>Limitations</h2> |
| <p>The consumer properties <code>group.id</code>, <code>auto.offset.reset</code> and <code>enable.auto.commit</code> cannot be set in <code>kafkaProperties</code> as they are set by the extension as <code>UUID.randomUUID().toString()</code>, <code>earliest</code> and <code>false</code> respectively. This is because the entire topic must be consumed by the Druid service from the very beginning so that a complete map of lookup values can be built. Setting any of these consumer properties will cause the extractor to not start.</p> |
| <p>Currently, the Kafka lookup extractor feeds the entire Kafka topic into a local cache. If you are using on-heap caching, this can easily clobber your java heap if the Kafka stream spews a lot of unique keys. Off-heap caching should alleviate these concerns, but there is still a limit to the quantity of data that can be stored. There is currently no eviction policy.</p> |
| <h2><a class="anchor" aria-hidden="true" id="testing-the-kafka-rename-functionality"></a><a href="#testing-the-kafka-rename-functionality" 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>Testing the Kafka rename functionality</h2> |
| <p>To test this setup, you can send key/value pairs to a Kafka stream via the following producer console:</p> |
| <pre><code class="hljs">./bin/kafka-console-producer.sh --<span class="hljs-keyword">property</span><span class="hljs-title"> </span>parse.<span class="hljs-attr">key=</span><span class="hljs-literal">true</span> --<span class="hljs-keyword">property</span><span class="hljs-title"> </span>key.<span class="hljs-attr">separator=</span><span class="hljs-string">"->"</span> --broker-list localhost:<span class="hljs-number">9092</span> --topic testTopic |
| </code></pre> |
| <p>Renames can then be published as <code>OLD_VAL->NEW_VAL</code> followed by newline (enter or return)</p> |
| </span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/26.0.0/development/extensions-core/hdfs.html"><span class="arrow-prev">← </span><span>HDFS</span></a><a class="docs-next button" href="/docs/26.0.0/development/extensions-core/lookups-cached-global.html"><span>Globally Cached Lookups</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#how-it-works">How it Works</a><ul class="toc-headings"><li><a href="#example">Example</a></li></ul></li><li><a href="#tombstones-and-deleting-records">Tombstones and Deleting Records</a></li><li><a href="#limitations">Limitations</a></li><li><a href="#testing-the-kafka-rename-functionality">Testing the Kafka rename functionality</a></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/26.0.0/">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 © 2022 <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/npm/docsearch.js@2/dist/cdn/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({ |
| appId: 'CPK9PMSCEY', |
| apiKey: 'd4ef4ffe3a2f0c7d1e34b062fd98736b', |
| indexName: 'apache_druid', |
| inputSelector: '#search_input_react', |
| algoliaOptions: {"facetFilters":["language:en","version:26.0.0"]} |
| }); |
| </script></body></html> |
