FLATTEN - Apache Drill

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alt="Slack logo" align="center"></a> </li> <li class='search-bar'> <form id="drill-search-form"> <input type="text" placeholder="Search Apache Drill" id="drill-search-term" /> <button type="submit"> <i class="fa fa-search"></i> </button> </form> </li> <li class="d"> <a href="/download/"> <i class="fa fa-cloud-download"></i> Download </a> </li> </ul> </div> <link href="/css/content.css" rel="stylesheet" type="text/css"> <aside class="sidebar"> <div class="docsidebar"> <div class="docsidebarwrapper"> <ul style="display: block;"> <li class="toctree-l1"><a href="javascript: void(0);">Getting Started</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/drill-introduction/">Drill Introduction</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/why-drill/">Why Drill</a></li> </ul> <li class="toctree-l1"><a href="javascript: void(0);">Architecture</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/architecture-introduction/">Architecture Introduction</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/drill-query-execution/">Drill Query Execution</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/core-modules/">Core Modules</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/performance/">Performance</a></li> </ul> <li class="toctree-l1"><a href="javascript: void(0);">Tutorials</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/tutorials-introduction/">Tutorials Introduction</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/drill-in-10-minutes/">Drill in 10 Minutes</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/analyzing-the-yelp-academic-dataset/">Analyzing the Yelp Academic Dataset</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Learn Drill with the MapR Sandbox</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/about-the-mapr-sandbox/">About the MapR Sandbox</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/installing-the-apache-drill-sandbox/">Installing the Apache Drill Sandbox</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/getting-to-know-the-drill-sandbox/">Getting to Know the Drill Sandbox</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/lesson-1-learn-about-the-data-set/">Lesson 1: Learn about the Data Set</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/lesson-2-run-queries-with-ansi-sql/">Lesson 2: Run Queries with ANSI SQL</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/lesson-3-run-queries-on-complex-data-types/">Lesson 3: Run Queries on Complex Data Types</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/summary/">Summary</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/analyzing-highly-dynamic-datasets/">Analyzing Highly Dynamic Datasets</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/analyzing-social-media/">Analyzing Social Media</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/analyzing-data-using-window-functions/">Analyzing Data Using Window Functions</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/orchestrating-queries-with-airflow/">Orchestrating queries with Airflow</a></li> </ul> <li class="toctree-l1"><a href="javascript: void(0);">Drill-on-YARN</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/drill-on-yarn-introduction/">Drill-on-YARN Introduction</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/creating-a-basic-drill-cluster/">Creating a Basic Drill Cluster</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/launch-drill-under-yarn/">Launch Drill Under YARN</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/configuration-reference/">Configuration Reference</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/drill-on-yarn-command-line-tool/">Drill-on-YARN Command-Line Tool</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/using-the-drill-on-yarn-web-ui/">Using the Drill-on-YARN Web UI</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/multiple-drill-clusters/">Multiple Drill Clusters</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/enabling-web-ui-security/">Enabling Web UI Security</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/appendix-a-release-note-issues/">Appendix A: Release Note Issues</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/appendix-b-drill-env-sh-settings/">Appendix B: drill-env.sh Settings</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/appendix-c-troubleshooting/">Appendix C: Troubleshooting</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/appendix-d-recreate-the-drill-archive/">Appendix D: Recreate the Drill Archive</a></li> </ul> <li class="toctree-l1"><a href="javascript: void(0);">Install Drill</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/install-drill-introduction/">Install Drill Introduction</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/migrating-parquet-data/">Migrating Parquet Data</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Installing Drill in Embedded Mode</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/embedded-mode-prerequisites/">Embedded Mode Prerequisites</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/running-drill-on-docker/">Running Drill on Docker</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/installing-drill-on-linux-and-mac-os-x/">Installing Drill on Linux and Mac OS X</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/starting-drill-on-linux-and-mac-os-x/">Starting Drill on Linux and Mac OS X</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/installing-drill-on-windows/">Installing Drill on Windows</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/starting-drill-on-windows/">Starting Drill on Windows</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">Installing Drill in Distributed Mode</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/distributed-mode-prerequisites/">Distributed Mode Prerequisites</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/installing-drill-on-the-cluster/">Installing Drill on the Cluster</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/starting-drill-in-distributed-mode/">Starting Drill in Distributed Mode</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/starting-the-web-ui/">Starting the Web UI</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/stopping-drill/">Stopping Drill</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/identifying-multiple-drill-versions-in-a-cluster/">Identifying Multiple Drill Versions in a Cluster</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Extended</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/installing-drill-in-distributed-mode-with-gcp-dataproc/">Installing Drill in Distributed Mode with GCP Dataproc</a></li> </ul> </ul> <li class="toctree-l1"><a href="javascript: void(0);">Configure Drill</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/configure-drill-introduction/">Configure Drill Introduction</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/configuring-drill-memory/">Configuring Drill Memory</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Securing Drill</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/securing-drill-introduction/">Securing Drill Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/secure-communication-paths/">Secure Communication Paths</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/roles-and-privileges/">Roles and Privileges</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-user-impersonation/">Configuring User Impersonation</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-inbound-impersonation/">Configuring Inbound Impersonation</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-user-impersonation-with-hive-authorization/">Configuring User Impersonation with Hive Authorization</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-user-security/">Configuring User Security</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-plain-security/">Configuring Plain Security</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-ssl-tls-for-encryption/">Configuring SSL/TLS for Encryption</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/using-libpam4j-as-the-pam-authenticator/">Using libpam4j as the PAM Authenticator</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/using-jpam-as-the-pam-authenticator/">Using jpam as the PAM Authenticator</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-htpasswd-file-authentication/">Configuring htpasswd file authentication</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-hashicorp-vault-authentication/">Configuring HashiCorp Vault authentication</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-kerberos-security/">Configuring Kerberos Security</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-drill-to-use-spnego-for-http-authentication/">Configuring Drill to use SPNEGO for HTTP Authentication</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-web-ui-and-rest-api-security/">Configuring Web UI and REST API Security</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-custom-acls-to-secure-znodes/">Configuring Custom ACLs to Secure znodes</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">Configuring a Multitenant Cluster</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-a-multitenant-cluster-introduction/">Configuring a Multitenant Cluster Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-multitenant-resources/">Configuring Multitenant Resources</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-resources-for-a-shared-drillbit/">Configuring Resources for a Shared Drillbit</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">Configuration Options</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/configuration-options-introduction/">Configuration Options Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/start-up-options/">Start-Up Options</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/planning-and-execution-options/">Planning and Execution Options</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/persistent-configuration-storage/">Persistent Configuration Storage</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/global-query-list/">Global Query List</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/ports-and-bind-addresses-used-by-drill/">Ports and Bind Addresses Used by Drill</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/configuring-the-drill-shell/">Configuring the Drill Shell</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/configuring-cgroups-to-control-cpu-usage/">Configuring cgroups to Control CPU Usage</a></li> </ul> <li class="toctree-l1"><a href="javascript: void(0);">Connect a Data Source</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/connect-a-data-source-introduction/">Connect a Data Source Introduction</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/storage-plugin-registration/">Storage Plugin Registration</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Storage Plugin Configuration</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/plugin-configuration-basics/">Plugin Configuration Basics</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-storage-plugins/">Configuring Storage Plugins</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/storage-plugin-authentication-modes/">Storage plugin authentication modes</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/workspaces/">Workspaces</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/drill-default-input-format/">Drill Default Input Format</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/file-system-storage-plugin/">File System Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/hbase-storage-plugin/">HBase Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/hive-storage-plugin/">Hive Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/rdbms-storage-plugin/">RDBMS Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/mongodb-storage-plugin/">MongoDB Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/mapr-db-format/">MapR-DB Format</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/s3-storage-plugin/">S3 Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/oci-os-storage-plugin/">OCI OS Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/opentsdb-storage-plugin/">OpenTSDB Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/kafka-storage-plugin/">Kafka Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/azure-blob-storage-plugin/">Azure Blob Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/druid-storage-plugin/">Druid Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/http-storage-plugin/">HTTP Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/elasticsearch-storage-plugin/">ElasticSearch Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/splunk-storage-plugin/">Splunk Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/cassandra-storage-plugin/">Cassandra Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/dropbox-storage-plugin/">Dropbox Storage Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/google-sheets-storage-plugin/">Google Sheets Storage Plugin</a></li> </ul> <li class="toctree-l1"><a href="javascript: void(0);">ODBC/JDBC Interfaces</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/interfaces-introduction/">Interfaces Introduction</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/using-the-jdbc-driver/">Using the JDBC Driver</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/using-jdbc-with-squirrel-on-windows/">Using JDBC with SQuirreL on Windows</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Installing the ODBC Driver</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/installing-the-driver-on-linux/">Installing the Driver on Linux</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/installing-the-driver-on-mac-os-x/">Installing the Driver on Mac OS X</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/installing-the-driver-on-windows/">Installing the Driver on Windows</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">Configuring ODBC</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/odbc-configuration-reference/">ODBC Configuration Reference</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/logging-and-tracing/">Logging and Tracing</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-odbc-on-linux/">Configuring ODBC on Linux</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-odbc-on-mac-os-x/">Configuring ODBC on Mac OS X</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-odbc-on-windows/">Configuring ODBC on Windows</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/testing-the-odbc-connection/">Testing the ODBC Connection</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">Using Drill Explorer</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/drill-explorer-introduction/">Drill Explorer Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/connecting-drill-explorer-to-data/">Connecting Drill Explorer to Data</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/browsing-data-and-defining-views/">Browsing Data and Defining Views</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">Using Drill with BI Tools</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/using-drill-with-bi-tools-introduction/">Using Drill with BI Tools Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/tableau-examples/">Tableau Examples</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/using-microstrategy-analytics-with-apache-drill/">Using MicroStrategy Analytics with Apache Drill</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/using-tibco-spotfire-desktop-with-drill/">Using Tibco Spotfire Desktop with Drill</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-tibco-spotfire-server-with-drill/">Configuring Tibco Spotfire Server with Drill</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/using-qlik-sense-with-drill/">Using Qlik Sense with Drill</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/using-apache-drill-with-tableau-10-2/">Using Apache Drill with Tableau 10.2</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/using-apache-drill-with-tableau-9-desktop/">Using Apache Drill with Tableau 9 Desktop</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/using-apache-drill-with-tableau-9-server/">Using Apache Drill with Tableau 9 Server</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/using-information-builders-webfocus-with-apache-drill/">Using Information Builders’ WebFOCUS with Apache Drill</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-jreport-with-drill/">Configuring JReport with Drill</a></li> </ul> </ul> <li class="toctree-l1"><a href="javascript: void(0);">Query Data</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/query-data-introduction/">Query Data Introduction</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Querying a File System</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/querying-a-file-system-introduction/">Querying a File System Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/querying-avro-files/">Querying Avro Files</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/querying-json-files/">Querying JSON Files</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/querying-parquet-files/">Querying Parquet Files</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/querying-plain-text-files/">Querying Plain Text Files</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/querying-directories/">Querying Directories</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/querying-sequence-files/">Querying Sequence Files</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/querying-hbase/">Querying HBase</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Querying Complex Data</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/querying-complex-data-introduction/">Querying Complex Data Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/sample-data-donuts/">Sample Data: Donuts</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/selecting-flat-data/">Selecting Flat Data</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/using-sql-functions-clauses-and-joins/">Using SQL Functions, Clauses, and Joins</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/selecting-nested-data-for-a-column/">Selecting Nested Data for a Column</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/selecting-multiple-columns-within-nested-data/">Selecting Multiple Columns Within Nested Data</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/querying-hive/">Querying Hive</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/querying-the-information-schema/">Querying the INFORMATION SCHEMA</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Querying Indexes</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/querying-indexes-introduction/">Querying Indexes Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/queries-that-qualify-for-index-based-query-plans/">Queries that Qualify for Index-Based Query Plans</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/types-of-indexes/">Types of Indexes</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/index-selection/">Index Selection</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/designing-indexes-for-your-queries/">Designing Indexes for Your Queries</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/configuring-index-planning/">Configuring Index Planning</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/verifying-index-use/">Verifying Index Use</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/querying-system-tables/">Querying System Tables</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/monitoring-and-canceling-queries-in-the-drill-web-ui/">Monitoring and Canceling Queries in the Drill Web UI</a></li> </ul> <li class="toctree-l1"><a href="javascript: void(0);">Performance Tuning</a></li> <ul style="display: none"> <li class="toctree-l2"><a href="javascript: void(0);">Drill Metastore</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/using-drill-metastore/">Using Drill Metastore</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/drill-iceberg-metastore/">Drill Iceberg Metastore</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/rdbms-metastore/">RDBMS Metastore</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/mongo-metastore/">Mongo Metastore</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/performance-tuning-introduction/">Performance Tuning Introduction</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Partition Pruning</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/partition-pruning-introduction/">Partition Pruning Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/how-to-partition-data/">How to Partition Data</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/asynchronous-parquet-reader/">Asynchronous Parquet Reader</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/optimizing-parquet-metadata-reading/">Optimizing Parquet Metadata Reading</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/parquet-filter-pushdown/">Parquet Filter Pushdown</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/hive-metadata-caching/">Hive Metadata Caching</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/choosing-a-storage-format/">Choosing a Storage Format</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Query Plans and Tuning</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/query-plans-and-tuning-introduction/">Query Plans and Tuning Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/join-planning-guidelines/">Join Planning Guidelines</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/guidelines-for-optimizing-aggregation/">Guidelines for Optimizing Aggregation</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/modifying-query-planning-options/">Modifying Query Planning Options</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/sort-based-and-hash-based-memory-constrained-operators/">Sort-Based and Hash-Based Memory-Constrained Operators</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/enabling-query-queuing/">Enabling Query Queuing</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/throttling/">Throttling</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/controlling-parallelization-to-balance-performance-with-multi-tenancy/">Controlling Parallelization to Balance Performance with Multi-Tenancy</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">Identifying Performance Issues</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/query-plans/">Query Plans</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/query-profiles/">Query Profiles</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">Performance Tuning Reference</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/query-profile-column-descriptions/">Query Profile Column Descriptions</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/physical-operators/">Physical Operators</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/monitoring-metrics/">Monitoring Metrics</a></li> </ul> <li class="toctree-l1"><a href="javascript: void(0);">Log and Debug</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/log-and-debug-introduction/">Log and Debug Introduction</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/error-messages/">Error Messages</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/modify-logback-xml/">Modify logback.xml</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/review-the-java-stack-trace/">Review the Java Stack Trace</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/query-audit-logging/">Query Audit Logging</a></li> </ul> <li class="toctree-l1 current_section "><a href="javascript: void(0);">SQL Reference</a></li> <ul class="current_section"> <li class="toctree-l2"><a class="reference internal" href="/docs/sql-reference-introduction/">SQL Reference Introduction</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Data Types</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/supported-data-types/">Supported Data Types</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/date-time-and-timestamp/">Date, Time, and Timestamp</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/handling-different-data-types/">Handling Different Data Types</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/lexical-structure/">Lexical Structure</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/operators/">Operators</a></li> <li class="toctree-l2"><a href="javascript: void(0);">SQL Functions</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/about-sql-function-examples/">About SQL Function Examples</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/math-and-trig/">Math and Trig</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/statistical/">Statistical</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/data-type-conversion/">Data Type Conversion</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/data-type-functions/">Data Type Functions</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/date-time-functions-and-arithmetic/">Date/Time Functions and Arithmetic</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/string-manipulation/">String Manipulation</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/aggregate-and-aggregate-statistical/">Aggregate and Aggregate Statistical</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/functions-for-handling-nulls/">Functions for Handling Nulls</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/phonetic-functions/">Phonetic Functions</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/string-distance-functions/">String Distance Functions</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/cryptography-functions/">Cryptography Functions</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/sql-dialect-compatibility-functions/">SQL dialect compatibility functions</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/gis-functions/">GIS functions</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/time-series-analysis-functions/">Time Series Analysis Functions</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/ip-networking-functions/">IP Networking functions</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">SQL Window Functions</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/sql-window-functions-introduction/">SQL Window Functions Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/aggregate-window-functions/">Aggregate Window Functions</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/ranking-window-functions/">Ranking Window Functions</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/value-window-functions/">Value Window Functions</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/sql-window-functions-examples/">SQL Window Functions Examples</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">Nested Data Functions</a></li> <ul style=""> <li class="toctree-l3"><a class="reference internal" href="/docs/nested-data-limitations/">Nested Data Limitations</a></li> <li class="toctree-l3 current"><a class="reference internal" href="/docs/flatten/">FLATTEN</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/kvgen/">KVGEN</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/repeated-count/">REPEATED_COUNT</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/repeated-contains/">REPEATED_CONTAINS</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/list-creation-functions/">COLLECT_LIST</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/query-directory-functions/">Query Directory Functions</a></li> <li class="toctree-l2"><a href="javascript: void(0);">SQL Commands</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/supported-sql-commands/">Supported SQL Commands</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/analyze-table-refresh-metadata/">ANALYZE TABLE REFRESH METADATA</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/analyze-table-compute-statistics/">ANALYZE TABLE COMPUTE STATISTICS</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/set/">SET</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/refresh-table-metadata/">REFRESH TABLE METADATA</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/reset/">RESET</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/alter-system/">ALTER SYSTEM</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/create-or-replace-schema/">CREATE OR REPLACE SCHEMA</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/create-table-as-ctas/">CREATE TABLE AS (CTAS)</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/create-temporary-table-as-cttas/">CREATE TEMPORARY TABLE AS (CTTAS)</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/create-function-using-jar/">CREATE FUNCTION USING JAR</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/partition-by-clause/">PARTITION BY Clause</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/create-view/">CREATE VIEW</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/describe/">DESCRIBE</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/drop-function-using-jar/">DROP FUNCTION USING JAR</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/drop-table/">DROP TABLE</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/drop-view/">DROP VIEW</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/explain/">EXPLAIN</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/lateral-join/">LATERAL Join</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/select/">SELECT</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/select-list/">SELECT List</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/from-clause/">FROM Clause</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/group-by-clause/">GROUP BY Clause</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/having-clause/">HAVING Clause</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/limit-clause/">LIMIT Clause</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/offset-clause/">OFFSET Clause</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/order-by-clause/">ORDER BY Clause</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/set-operators/">Set Operators</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/where-clause/">WHERE Clause</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/with-clause/">WITH Clause</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/show-databases-and-show-schemas/">SHOW DATABASES and SHOW SCHEMAS</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/show-files/">SHOW FILES</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/show-tables/">SHOW TABLES</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/use/">USE</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/pivot-operators/">Pivot Operators</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">SQL Conditional Expressions</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/case/">CASE</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/reserved-keywords/">Reserved Keywords</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/sql-extensions/">SQL Extensions</a></li> </ul> <li class="toctree-l1"><a href="javascript: void(0);">Data Sources and File Formats</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/data-sources-and-file-formats-introduction/">Data Sources and File Formats Introduction</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/hive-to-drill-data-type-mapping/">Hive-to-Drill Data Type Mapping</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/deploying-and-using-a-hive-udf/">Deploying and Using a Hive UDF</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/parquet-format/">Parquet Format</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/logfile-plugin/">Logfile Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/json-data-model/">JSON Data Model</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/text-files-csv-tsv-psv/">Text Files: CSV, TSV, PSV</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/sequence-files/">Sequence Files</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/httpd-format-plugin/">HTTPD Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/image-metadata-format-plugin/">Image Metadata Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/syslog-format-plugin/">Syslog Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/ltsv-format-plugin/">LTSV Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/spss-format-plugin/">SPSS Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/esri-shapefile-format-plugin/">ESRI Shapefile Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/excel-format-plugin/">Excel Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/hdf5-format-plugin/">HDF5 Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/ms-access-format-plugin/">Microsoft Access Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/xml-format-plugin/">XML Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/iceberg-format-plugin/">Iceberg Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/delta-lake-format-plugin/">Delta Lake Format Plugin</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/sas-format-plugin/">SAS Format Plugin</a></li> </ul> <li class="toctree-l1"><a href="javascript: void(0);">Develop Custom Functions</a></li> <ul style="display: none"> <li class="toctree-l2"><a class="reference internal" href="/docs/develop-custom-functions-introduction/">Develop Custom Functions Introduction</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/developing-a-simple-function/">Developing a Simple Function</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/tutorial-develop-a-simple-function/">Tutorial: Develop a Simple Function</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/developing-an-aggregate-function/">Developing an Aggregate Function</a></li> <li class="toctree-l2"><a href="javascript: void(0);">Adding Custom Functions to Drill</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/adding-custom-functions-to-drill-introduction/">Adding Custom Functions to Drill Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/manually-adding-custom-functions-to-drill/">Manually Adding Custom Functions to Drill</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/creating-custom-authenticators/">Creating Custom Authenticators</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/dynamic-udfs/">Dynamic UDFs</a></li> </ul> <li class="toctree-l2"><a class="reference internal" href="/docs/using-custom-functions-in-queries/">Using Custom Functions in Queries</a></li> <li class="toctree-l2"><a class="reference internal" href="/docs/custom-function-interfaces/">Custom Function Interfaces</a></li> </ul> <li class="toctree-l1"><a class="reference internal" href="/docs/troubleshooting/">Troubleshooting</a></li> <li class="toctree-l1"><a href="javascript: void(0);">Developer Information</a></li> <ul style="display: none"> <li class="toctree-l2"><a href="javascript: void(0);">REST API</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/rest-api-introduction/">REST API Introduction</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/submitting-queries-from-the-rest-api-when-impersonation-is-enabled-and-authentication-is-disabled/">Submitting Queries from the REST API when Impersonation is Enabled and Authentication is Disabled</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/use-postman-to-run-sql-queries-on-drill-data-sources/">Use Postman to Run SQL Queries on Drill Data Sources</a></li> </ul> <li class="toctree-l2"><a href="javascript: void(0);">Develop Drill</a></li> <ul style="display: none"> <li class="toctree-l3"><a class="reference internal" href="/docs/compiling-drill-from-source/">Compiling Drill from Source</a></li> <li class="toctree-l3"><a class="reference internal" href="/docs/useful-information-for-drill-developers/">Useful Information for Drill Developers</a></li> </ul> <li class="toctree-l2"><a href="javascript: 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class="main-content-wrapper"> <div class="main-content"> <a class="edit-link" href="https://github.com/apache/drill-site/blob/master/_docs/en/sql-reference/nested-data-functions/010-flatten.md" target="_blank"><i class="fa fa-pencil-square-o"></i></a> <div class="int_title left"> <h1>FLATTEN</h1> </div>  <div class="int_text" align="left"> <p>FLATTEN separates the elements in a repeated field into individual records.</p> <h2 id="syntax">Syntax</h2> <div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>FLATTEN(z) </code></pre></div></div> <p><em>z</em> is a JSON array.</p> <h2 id="usage-notes">Usage Notes</h2> <p>The FLATTEN function is useful for flexible exploration of repeated data.</p> <p>To maintain the association between each flattened value and the other fields in the record, the FLATTEN function copies all of the other columns into each new record.</p> <p>A very simple example would turn this data (one record):</p> <div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>{ "x" : 5, "y" : "a string", "z" : [ 1,2,3] } </code></pre></div></div> <p>into three distinct records:</p> <div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>SELECT FLATTEN(z) FROM table; | x | y | z | |-------------|----------------|-----------| | 5 | "a string" | 1 | | 5 | "a string" | 2 | | 5 | "a string" | 3 | </code></pre></div></div> <p>The function takes a single argument, which must be an array (the <code class="language-plaintext highlighter-rouge">z</code> column in this example).</p> <p>Using the all (*) wildcard as the argument to flatten is not supported and returns an error.</p> <h2 id="examples">Examples</h2> <p>For a more interesting example, consider the JSON data in the publicly available <a href="https://www.yelp.com/dataset_challenge/dataset">Yelp</a> data set. The first query below returns three columns from the <code class="language-plaintext highlighter-rouge">yelp_academic_dataset_business.json</code> file: <code class="language-plaintext highlighter-rouge">name</code>, <code class="language-plaintext highlighter-rouge">hours</code>, and <code class="language-plaintext highlighter-rouge">categories</code>. The query is restricted to distinct rows where the name is <code class="language-plaintext highlighter-rouge">z</code><code class="language-plaintext highlighter-rouge">pizza</code>. The query returns only one row that meets those criteria; however, note that this row contains an array of four categories:</p> <div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>0: jdbc:drill:zk=local> select distinct name, hours, categories from dfs.yelp.`yelp_academic_dataset_business.json` where name ='zpizza'; |------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------| | name | hours | categories | |------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------| | zpizza | {"Tuesday":{"close":"22:00","open":"10:00"},"Friday":{"close":"23:00","open":"10:00"},"Monday":{"close":"22:00","open":"10:00"},"Wednesday":{"close":"22:00","open":"10:00"},"Thursday":{"close":"22:00","open":"10:00"},"Sunday":{"close":"22:00","open":"10:00"},"Saturday":{"close":"23:00","open":"10:00"}} | ["Gluten-Free","Pizza","Vegan","Restaurants"] | </code></pre></div></div> <p>The FLATTEN function can operate on this single row and return multiple rows, one for each category:</p> <div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>0: jdbc:drill:zk=local> select distinct name, flatten(categories) as categories from dfs.yelp.`yelp_academic_dataset_business.json` where name ='zpizza' order by 2; |------------|-------------| | name | categories | |------------|-------------| | zpizza | Gluten-Free | | zpizza | Pizza | | zpizza | Restaurants | | zpizza | Vegan | |------------|-------------| 4 rows selected (2.797 seconds) </code></pre></div></div> <p>Having used the FLATTEN function to break down arrays into distinct rows, you can run queries that do deeper analysis on the flattened result set. For example, you can use FLATTEN in a subquery, then apply WHERE clause constraints or aggregate functions to the results in the outer query.</p> <p>The following query uses the same data file as the previous query to flatten the categories array, then run a COUNT function on the flattened result:</p> <div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>select celltbl.catl, count(celltbl.catl) catcount from (select flatten(categories) catl from dfs.yelp.`yelp_academic_dataset_business.json`) celltbl group by celltbl.catl order by count(celltbl.catl) desc limit 5; |---------------|------------| | catl | catcount | |---------------|------------| | Restaurants | 14303 | | Shopping | 6428 | | Food | 5209 | | Beauty & Spas | 3421 | | Nightlife | 2870 | |---------------|------------| </code></pre></div></div> <p>A common use case for FLATTEN is its use in conjunction with the KVGEN function as shown in the section, <a href="/docs/json-data-model/">“JSON Data Model”</a>.</p> <div class="doc-nav"> <span class="previous-toc"><a href="/docs/nested-data-limitations/">← Nested Data Limitations</a></span><span class="next-toc"><a href="/docs/kvgen/">KVGEN →</a></span> </div> </div> </div> </div> </div> <p class="push"></p> <div id="footer" class="mw"> <div class="wrapper"> Copyright © 2012-2022 The Apache Software Foundation, licensed under the Apache License, Version 2.0.<br> Apache and the Apache feather logo are trademarks of The Apache Software Foundation. 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