| <!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>Cached Lookup Module · Apache Druid</title><meta name="viewport" content="width=device-width"/><link rel="canonical" href="https://druid.apache.org/docs/latest/development/extensions-core/druid-lookups.html"/><meta name="generator" content="Docusaurus"/><meta name="description" content="<!--"/><meta name="docsearch:language" content="en"/><meta name="docsearch:version" content="0.20.0" /><meta property="og:title" content="Cached Lookup Module · 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/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/tutorials/docker.html">Docker</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">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><li class="navListItem"><a class="navItem" href="/docs/latest/querying/querying.html">Native queries</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/query-execution.html">Query execution</a></li><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Concepts</h4><ul><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/joins.html">Joins</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/multi-value-dimensions.html">Multi-value dimensions</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/multitenancy.html">Multitenancy</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/querying/query-context.html">Context parameters</a></li></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Native query types</h4><ul><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/searchquery.html">Search</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></ul></div><div class="navGroup subNavGroup"><h4 class="navGroupSubcategoryTitle">Native query components</h4><ul><li class="navListItem"><a class="navItem" href="/docs/latest/querying/filters.html">Filters</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/granularities.html">Granularities</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/dimensionspecs.html">Dimensions</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/post-aggregations.html">Post-aggregations</a></li><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/querying/having.html">Having filters (groupBy)</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/limitspec.html">Sorting and limiting (groupBy)</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/topnmetricspec.html">Sorting (topN)</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/querying/sorting-orders.html">String comparators</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/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/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/druid-console.html">Web console</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/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/management-uis.html">Legacy Management UIs</a></li><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/export-metadata.html">Export Metadata Tool</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/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"><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/azure.html">Microsoft Azure</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 navListItemActive"><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/druid-ranger-security.html">Apache Ranger Security</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/druid-pac4j.html">Druid pac4j based Security 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/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/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">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/development/extensions-contrib/gce-extensions.html">GCE Extensions</a></li><li class="navListItem"><a class="navItem" href="/docs/latest/development/extensions-contrib/aliyun-oss.html">Aliyun OSS</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/select-query.html">Select</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 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/druid-lookups.md" target="_blank" rel="noreferrer noopener">Edit</a><h1 id="__docusaurus" class="postHeaderTitle">Cached Lookup Module</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. |
| --> |
| <blockquote> |
| <p>Please note that this is an experimental module and the development/testing still at early stage. Feel free to try it and give us your feedback.</p> |
| </blockquote> |
| <h2><a class="anchor" aria-hidden="true" id="description"></a><a href="#description" 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>Description</h2> |
| <p>This Apache Druid module provides a per-lookup caching mechanism for JDBC data sources. |
| The main goal of this cache is to speed up the access to a high latency lookup sources and to provide a caching isolation for every lookup source. |
| Thus user can define various caching strategies or and implementation per lookup, even if the source is the same. |
| This module can be used side to side with other lookup module like the global cached lookup module.</p> |
| <p>To use this extension please make sure to <a href="/docs/latest/development/extensions.html#loading-extensions">include</a> <code>druid-lookups-cached-single</code> as an extension.</p> |
| <blockquote> |
| <p>If using JDBC, you will need to add your database's client JAR files to the extension's directory. |
| For Postgres, the connector JAR is already included. |
| For MySQL, you can get it from <a href="https://dev.mysql.com/downloads/connector/j/">https://dev.mysql.com/downloads/connector/j/</a>. |
| Copy or symlink the downloaded file to <code>extensions/druid-lookups-cached-single</code> under the distribution root directory.</p> |
| </blockquote> |
| <h2><a class="anchor" aria-hidden="true" id="architecture"></a><a href="#architecture" 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>Architecture</h2> |
| <p>Generally speaking this module can be divided into two main component, namely, the data fetcher layer and caching layer.</p> |
| <h3><a class="anchor" aria-hidden="true" id="data-fetcher-layer"></a><a href="#data-fetcher-layer" 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>Data Fetcher layer</h3> |
| <p>First part is the data fetcher layer API <code>DataFetcher</code>, that exposes a set of fetch methods to fetch data from the actual Lookup dimension source. |
| For instance <code>JdbcDataFetcher</code> provides an implementation of <code>DataFetcher</code> that can be used to fetch key/value from a RDBMS via JDBC driver. |
| If you need new type of data fetcher, all you need to do, is to implement the interface <code>DataFetcher</code> and load it via another druid module.</p> |
| <h3><a class="anchor" aria-hidden="true" id="caching-layer"></a><a href="#caching-layer" 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>Caching layer</h3> |
| <p>This extension comes with two different caching strategies. First strategy is a poll based and the second is a load based.</p> |
| <h4><a class="anchor" aria-hidden="true" id="poll-lookup-cache"></a><a href="#poll-lookup-cache" 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>Poll lookup cache</h4> |
| <p>The poll strategy cache strategy will fetch and swap all the pair of key/values periodically from the lookup source. |
| Hence, user should make sure that the cache can fit all the data. |
| The current implementation provides 2 type of poll cache, the first is on-heap (uses immutable map), while the second uses MapDB based off-heap map. |
| User can also implement a different lookup polling cache by implementing <code>PollingCacheFactory</code> and <code>PollingCache</code> interfaces.</p> |
| <h4><a class="anchor" aria-hidden="true" id="loading-lookup"></a><a href="#loading-lookup" 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>Loading lookup</h4> |
| <p>Loading cache strategy will load the key/value pair upon request on the key it self, the general algorithm is load key if absent. |
| Once the key/value pair is loaded eviction will occur according to the cache eviction policy. |
| This module comes with two loading lookup implementation, the first is on-heap backed by a Guava cache implementation, the second is MapDB off-heap implementation. |
| Both implementations offer various eviction strategies. |
| Same for Loading cache, developer can implement a new type of loading cache by implementing <code>LookupLoadingCache</code> interface.</p> |
| <h2><a class="anchor" aria-hidden="true" id="configuration-and-operation"></a><a href="#configuration-and-operation" 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>Configuration and Operation:</h2> |
| <h3><a class="anchor" aria-hidden="true" id="polling-lookup"></a><a href="#polling-lookup" 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>Polling Lookup</h3> |
| <p><strong>Note that the current implementation of <code>offHeapPolling</code> and <code>onHeapPolling</code> will create two caches one to lookup value based on key and the other to reverse lookup the key from value</strong></p> |
| <table> |
| <thead> |
| <tr><th>Field</th><th>Type</th><th>Description</th><th>Required</th><th>default</th></tr> |
| </thead> |
| <tbody> |
| <tr><td>dataFetcher</td><td>JSON object</td><td>Specifies the lookup data fetcher type to use in order to fetch data</td><td>yes</td><td>null</td></tr> |
| <tr><td>cacheFactory</td><td>JSON Object</td><td>Cache factory implementation</td><td>no</td><td>onHeapPolling</td></tr> |
| <tr><td>pollPeriod</td><td>Period</td><td>polling period</td><td>no</td><td>null (poll once)</td></tr> |
| </tbody> |
| </table> |
| <h5><a class="anchor" aria-hidden="true" id="example-of-polling-on-heap-lookup"></a><a href="#example-of-polling-on-heap-lookup" 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 of Polling On-heap Lookup</h5> |
| <p>This example demonstrates a polling cache that will update its on-heap cache every 10 minutes</p> |
| <pre><code class="hljs css language-json">{ |
| <span class="hljs-attr">"type"</span>:<span class="hljs-string">"pollingLookup"</span>, |
| <span class="hljs-attr">"pollPeriod"</span>:<span class="hljs-string">"PT10M"</span>, |
| <span class="hljs-attr">"dataFetcher"</span>:{ <span class="hljs-attr">"type"</span>:<span class="hljs-string">"jdbcDataFetcher"</span>, <span class="hljs-attr">"connectorConfig"</span>:<span class="hljs-string">"jdbc://mysql://localhost:3306/my_data_base"</span>, <span class="hljs-attr">"table"</span>:<span class="hljs-string">"lookup_table_name"</span>, <span class="hljs-attr">"keyColumn"</span>:<span class="hljs-string">"key_column_name"</span>, <span class="hljs-attr">"valueColumn"</span>: <span class="hljs-string">"value_column_name"</span>}, |
| <span class="hljs-attr">"cacheFactory"</span>:{<span class="hljs-attr">"type"</span>:<span class="hljs-string">"onHeapPolling"</span>} |
| } |
| |
| </code></pre> |
| <h5><a class="anchor" aria-hidden="true" id="example-polling-off-heap-lookup"></a><a href="#example-polling-off-heap-lookup" 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 Polling Off-heap Lookup</h5> |
| <p>This example demonstrates an off-heap lookup that will be cached once and never swapped <code>(pollPeriod == null)</code></p> |
| <pre><code class="hljs css language-json">{ |
| <span class="hljs-attr">"type"</span>:<span class="hljs-string">"pollingLookup"</span>, |
| <span class="hljs-attr">"dataFetcher"</span>:{ <span class="hljs-attr">"type"</span>:<span class="hljs-string">"jdbcDataFetcher"</span>, <span class="hljs-attr">"connectorConfig"</span>:<span class="hljs-string">"jdbc://mysql://localhost:3306/my_data_base"</span>, <span class="hljs-attr">"table"</span>:<span class="hljs-string">"lookup_table_name"</span>, <span class="hljs-attr">"keyColumn"</span>:<span class="hljs-string">"key_column_name"</span>, <span class="hljs-attr">"valueColumn"</span>: <span class="hljs-string">"value_column_name"</span>}, |
| <span class="hljs-attr">"cacheFactory"</span>:{<span class="hljs-attr">"type"</span>:<span class="hljs-string">"offHeapPolling"</span>} |
| } |
| |
| </code></pre> |
| <h3><a class="anchor" aria-hidden="true" id="loading-lookup-1"></a><a href="#loading-lookup-1" 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>Loading lookup</h3> |
| <table> |
| <thead> |
| <tr><th>Field</th><th>Type</th><th>Description</th><th>Required</th><th>default</th></tr> |
| </thead> |
| <tbody> |
| <tr><td>dataFetcher</td><td>JSON object</td><td>Specifies the lookup data fetcher type to use in order to fetch data</td><td>yes</td><td>null</td></tr> |
| <tr><td>loadingCacheSpec</td><td>JSON Object</td><td>Lookup cache spec implementation</td><td>yes</td><td>null</td></tr> |
| <tr><td>reverseLoadingCacheSpec</td><td>JSON Object</td><td>Reverse lookup cache implementation</td><td>yes</td><td>null</td></tr> |
| </tbody> |
| </table> |
| <h5><a class="anchor" aria-hidden="true" id="example-loading-on-heap-guava"></a><a href="#example-loading-on-heap-guava" 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 Loading On-heap Guava</h5> |
| <p>Guava cache configuration spec.</p> |
| <table> |
| <thead> |
| <tr><th>Field</th><th>Type</th><th>Description</th><th>Required</th><th>default</th></tr> |
| </thead> |
| <tbody> |
| <tr><td>concurrencyLevel</td><td>int</td><td>Allowed concurrency among update operations</td><td>no</td><td>4</td></tr> |
| <tr><td>initialCapacity</td><td>int</td><td>Initial capacity size</td><td>no</td><td>null</td></tr> |
| <tr><td>maximumSize</td><td>long</td><td>Specifies the maximum number of entries the cache may contain.</td><td>no</td><td>null (infinite capacity)</td></tr> |
| <tr><td>expireAfterAccess</td><td>long</td><td>Specifies the eviction time after last read in milliseconds.</td><td>no</td><td>null (No read-time-based eviction when set to null)</td></tr> |
| <tr><td>expireAfterWrite</td><td>long</td><td>Specifies the eviction time after last write in milliseconds.</td><td>no</td><td>null (No write-time-based eviction when set to null)</td></tr> |
| </tbody> |
| </table> |
| <pre><code class="hljs css language-json">{ |
| <span class="hljs-attr">"type"</span>:<span class="hljs-string">"loadingLookup"</span>, |
| <span class="hljs-attr">"dataFetcher"</span>:{ <span class="hljs-attr">"type"</span>:<span class="hljs-string">"jdbcDataFetcher"</span>, <span class="hljs-attr">"connectorConfig"</span>:<span class="hljs-string">"jdbc://mysql://localhost:3306/my_data_base"</span>, <span class="hljs-attr">"table"</span>:<span class="hljs-string">"lookup_table_name"</span>, <span class="hljs-attr">"keyColumn"</span>:<span class="hljs-string">"key_column_name"</span>, <span class="hljs-attr">"valueColumn"</span>: <span class="hljs-string">"value_column_name"</span>}, |
| <span class="hljs-attr">"loadingCacheSpec"</span>:{<span class="hljs-attr">"type"</span>:<span class="hljs-string">"guava"</span>}, |
| <span class="hljs-attr">"reverseLoadingCacheSpec"</span>:{<span class="hljs-attr">"type"</span>:<span class="hljs-string">"guava"</span>, <span class="hljs-attr">"maximumSize"</span>:<span class="hljs-number">500000</span>, <span class="hljs-attr">"expireAfterAccess"</span>:<span class="hljs-number">100000</span>, <span class="hljs-attr">"expireAfterAccess"</span>:<span class="hljs-number">10000</span>} |
| } |
| </code></pre> |
| <h5><a class="anchor" aria-hidden="true" id="example-loading-off-heap-mapdb"></a><a href="#example-loading-off-heap-mapdb" 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 Loading Off-heap MapDB</h5> |
| <p>Off heap cache is backed by <a href="http://www.mapdb.org/">MapDB</a> implementation. MapDB is using direct memory as memory pool, please take that into account when limiting the JVM direct memory setup.</p> |
| <table> |
| <thead> |
| <tr><th>Field</th><th>Type</th><th>Description</th><th>Required</th><th>default</th></tr> |
| </thead> |
| <tbody> |
| <tr><td>maxStoreSize</td><td>double</td><td>maximal size of store in GB, if store is larger entries will start expiring</td><td>no</td><td>0</td></tr> |
| <tr><td>maxEntriesSize</td><td>long</td><td>Specifies the maximum number of entries the cache may contain.</td><td>no</td><td>0 (infinite capacity)</td></tr> |
| <tr><td>expireAfterAccess</td><td>long</td><td>Specifies the eviction time after last read in milliseconds.</td><td>no</td><td>0 (No read-time-based eviction when set to null)</td></tr> |
| <tr><td>expireAfterWrite</td><td>long</td><td>Specifies the eviction time after last write in milliseconds.</td><td>no</td><td>0 (No write-time-based eviction when set to null)</td></tr> |
| </tbody> |
| </table> |
| <pre><code class="hljs css language-json">{ |
| <span class="hljs-attr">"type"</span>:<span class="hljs-string">"loadingLookup"</span>, |
| <span class="hljs-attr">"dataFetcher"</span>:{ <span class="hljs-attr">"type"</span>:<span class="hljs-string">"jdbcDataFetcher"</span>, <span class="hljs-attr">"connectorConfig"</span>:<span class="hljs-string">"jdbc://mysql://localhost:3306/my_data_base"</span>, <span class="hljs-attr">"table"</span>:<span class="hljs-string">"lookup_table_name"</span>, <span class="hljs-attr">"keyColumn"</span>:<span class="hljs-string">"key_column_name"</span>, <span class="hljs-attr">"valueColumn"</span>: <span class="hljs-string">"value_column_name"</span>}, |
| <span class="hljs-attr">"loadingCacheSpec"</span>:{<span class="hljs-attr">"type"</span>:<span class="hljs-string">"mapDb"</span>, <span class="hljs-attr">"maxEntriesSize"</span>:<span class="hljs-number">100000</span>}, |
| <span class="hljs-attr">"reverseLoadingCacheSpec"</span>:{<span class="hljs-attr">"type"</span>:<span class="hljs-string">"mapDb"</span>, <span class="hljs-attr">"maxStoreSize"</span>:<span class="hljs-number">5</span>, <span class="hljs-attr">"expireAfterAccess"</span>:<span class="hljs-number">100000</span>, <span class="hljs-attr">"expireAfterAccess"</span>:<span class="hljs-number">10000</span>} |
| } |
| </code></pre> |
| </span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/latest/development/extensions-core/druid-kerberos.html"><span class="arrow-prev">← </span><span>Kerberos</span></a><a class="docs-next button" href="/docs/latest/development/extensions-core/druid-ranger-security.html"><span>Apache Ranger Security</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#description">Description</a></li><li><a href="#architecture">Architecture</a><ul class="toc-headings"><li><a href="#data-fetcher-layer">Data Fetcher layer</a></li><li><a href="#caching-layer">Caching layer</a></li></ul></li><li><a href="#configuration-and-operation">Configuration and Operation:</a><ul class="toc-headings"><li><a href="#polling-lookup">Polling Lookup</a></li><li><a href="#loading-lookup-1">Loading lookup</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:0.20.0"]} |
| }); |
| </script></body></html> |
