| <!DOCTYPE html> |
| <html lang="en"> |
| <head> |
| <meta charset="utf-8"> |
| <meta name="viewport" content="width=device-width,initial-scale=1.0"> |
| <title>Untitled | Apache Cassandra Documentation</title> |
| <link rel="stylesheet" href="../../../../../assets/css/site.css"> |
| <link rel="schema.dcterms" href="https://purl.org/dc/terms/"> |
| <meta name="dcterms.subject" content="Cassandra"> |
| <meta name="dcterms.identifier" content="5.0"> |
| <meta name="generator" content="Antora 2.3.4"> |
| <link rel="icon" href="../../../../../assets/img/favicon.ico" type="image/x-icon"> |
| <script> |
| const script = document.createElement("script"); |
| const domain = window.location.hostname; |
| script.type = "text/javascript"; |
| script.src = "https://plausible.cassandra.apache.org/js/plausible.js"; |
| script.setAttribute("data-domain",domain); |
| script.setAttribute("defer",'true'); |
| script.setAttribute("async",'true'); |
| document.getElementsByTagName("head")[0].appendChild(script); |
| </script> </head> |
| <body class="docs-wrapper article"> |
| <div class="container mx-auto relative"> |
| <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script> |
| <meta property="og:type" content="website" /> |
| <meta property="og:url" content="/" /> |
| <meta property="og:site_name" content="Apache Cassandra" /> |
| |
| <header id="top-nav"> |
| <div class="inner relative"> |
| <div class="header-social-icons text-right"> |
| <a href="https://twitter.com/cassandra?lang=en" target="_blank" styles="margin-left: 20px;"><img src="../../../../../assets/img/twitter-icon-circle-white.svg" alt="twitter icon" width="24"></a> |
| <a href="https://www.linkedin.com/company/apache-cassandra/" target="_blank" styles="margin-left: 20px;"><img src="../../../../../assets/img/LI-In-Bug.png" alt="linked-in icon" width="24"></a> |
| <a href="https://www.youtube.com/c/PlanetCassandra" target="_blank" styles="margin-left: 20px;"><img src="../../../../../assets/img/youtube-icon.png" alt="youtube icon" width="24"></a> |
| </div> |
| <div class="cf"> |
| <div class="logo left"><a href="/"><img src="../../../../../assets/img/logo-white-r.png" alt="Cassandra Logo"></a></div> |
| <div class="mobile-nav-icon right"> |
| <img class="toggle-icon" src="../../../../../assets/img/hamburger-nav.svg"> |
| </div> |
| <ul class="main-nav nav-links right flex flex-vert-center flex-space-between"> |
| <li> |
| <a class="nav-link hide-mobile">Get Started</a> |
| <ul class="sub-menu bg-white"> |
| <li class="pa-micro"> |
| <a href="/_/cassandra-basics.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-basics.png" alt="cassandra basics icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Cassandra Basics |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro"> |
| <a href="/_/quickstart.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-rocket.png" alt="cassandra basics icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Quickstart |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro"> |
| <a href="/_/ecosystem.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-ecosystem.png" alt="cassandra basics icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Ecosystem |
| </div> |
| </a> |
| </li> |
| </ul> |
| </li> |
| <li><a class="nav-link" href="/doc/latest/">Documentation</a></li> |
| <li> |
| <a class="nav-link" href="/_/community.html">Community</a> |
| <ul class="sub-menu bg-white"> |
| <li class="pa-micro"> |
| <a href="/_/community.html#code-of-conduct"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-welcome.png" alt="welcome icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Welcome |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/community.html#discussions"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-discussions.png" alt="discussions icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Discussions |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/community.html#project-governance"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-governance.png" alt="Governance icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Governance |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/community.html#how-to-contribute"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-contribute.png" alt="Contribute icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Contribute |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/community.html#meet-the-community"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-community.png" alt="Meet the Community icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Meet the Community |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/cassandra-catalyst-program.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-catalyst.png" alt="Catalyst icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Catalyst Program |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/events.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-events.png" alt="Events icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Events |
| </div> |
| </a> |
| </li> |
| </ul> |
| </li> |
| <li> |
| <a class="nav-link hide-mobile">Learn</a> |
| <ul class="sub-menu bg-white"> |
| <li class="pa-micro"> |
| <a href="/_/Apache-Cassandra-5.0-Moving-Toward-an-AI-Driven-Future.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-basics.png" alt="Basics icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Cassandra 5.0 |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro"> |
| <a href="/_/case-studies.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-case-study.png" alt="Case Studies icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Case Studies |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro"> |
| <a href="/_/resources.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-resources.png" alt="Resources icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Resources |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro"> |
| <a href="/_/blog.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../../assets/img/sub-menu-blog.png" alt="Blog icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Blog |
| </div> |
| </a> |
| </li> |
| </ul> |
| </li> |
| <li><a class="nav-link btn btn--filled" href="/_/download.html">Download Now</a></li> |
| </ul> |
| </div> |
| </div> |
| </header> |
| |
| <div class="hero hero--home grad"> |
| <div class="eye"></div> |
| <div id="docs-content" class="text-center flex flex-center flex-column relative z2 ma-xlarge"> |
| <h2>Cassandra Documentation</h2> |
| </div> |
| </div> |
| <div class="body px-medium py-medium container"> |
| <div class="docs-nav-bar flex flex-space-between mb-medium"> |
| <div id="mobile-docs-nav-burger" class="hidden"> |
| <svg viewBox="0 0 24 24" width="36" height="36" stroke="#1c81a0" stroke-width="2.5" fill="none" stroke-linecap="round" stroke-linejoin="round" class="css-i6dzq1"><line x1="3" y1="12" x2="21" y2="12"></line><line x1="3" y1="6" x2="21" y2="6"></line><line x1="3" y1="18" x2="21" y2="18"></line></svg> |
| </div> |
| <div class="docs-nav-item relative"> |
| <input id="search-input" type="text" placeholder="Search docs"> |
| </div> |
| <div class="versions-wrapper"> |
| <h4>Version:</h4> |
| <div class="nav-panel-explore" data-panel="explore"> |
| |
| <div id="version-toggle" class="context"> |
| <span class="version">5.0</span> |
| </div> |
| <ul id="versions-list" class="components"> |
| <li class="component"> |
| <ul class="versions"> |
| <li class="version is-latest"> |
| <a href="../../../../../_/index.html">master</a> |
| </li> |
| </ul> |
| </li> |
| <li class="component is-current"> |
| <ul class="versions"> |
| <li class="version"> |
| <a href="../../../../trunk/index.html">trunk</a> |
| </li> |
| <li class="version is-current"> |
| <a href="../../../index.html">5.0</a> |
| </li> |
| <li class="version is-latest"> |
| <a href="../../../../4.1/index.html">4.1</a> |
| </li> |
| <li class="version"> |
| <a href="../../../../4.0/index.html">4.0</a> |
| </li> |
| <li class="version"> |
| <a href="../../../../3.11/index.html">3.11</a> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </div> |
| </div> </div> |
| <div class="cf relative"> |
| <nav class="nav docs-nav full-800"> |
| <div class="nav-menu"> |
| <ul class="nav-list"> |
| <li class="nav-item is-active" data-depth="0"> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="1"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../../index.html">Main</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/glossary.html">Glossary</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/bugs.html">How to report bugs</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/contactus.html">Contact us</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../../../../_/development/index.html">Development</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/development/gettingstarted.html">Getting started</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/development/ide.html">Building and IDE integration</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/development/testing.html">Testing</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/development/patches.html">Contributing code changes</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/development/code_style.html">Code style</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/development/how_to_review.html">Review checklist</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/development/how_to_commit.html">How to commit</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/development/documentation.html">Working on documentation</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/development/ci.html">Jenkins CI environment</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/development/dependencies.html">Dependency management</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../../_/development/release_process.html">Release process</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item is-active" data-depth="0"> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="1"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <span class="nav-text">Cassandra</span> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../overview/faq/index.html">FAQ</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../getting-started/index.html">Getting Started</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../getting-started/cassandra-quickstart.html">Cassandra Quickstart</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../getting-started/sai-quickstart.html">SAI Quickstart</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../getting-started/vector-search-quickstart.html">Vector Search Quickstart</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../installing/installing.html">Installing Cassandra</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../getting-started/configuring.html">Configuring Cassandra</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../getting-started/querying.html">Inserting and querying</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../getting-started/drivers.html">Client drivers</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../getting-started/production.html">Production recommendations</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../new/index.html">What’s new</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../java17.html">Support for Java</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../architecture/index.html">Architecture</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../architecture/overview.html">Overview</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../architecture/dynamo.html">Dynamo</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../architecture/storage-engine.html">Storage Engine</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../architecture/guarantees.html">Guarantees</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../architecture/messaging.html">Improved Internode Messaging</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../architecture/streaming.html">Improved Streaming</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../developing/data-modeling/index.html">Data Modeling</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/data-modeling/intro.html">Introduction</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/data-modeling/data-modeling_conceptual.html">Conceptual data modeling</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/data-modeling/data-modeling_rdbms.html">RDBMS design</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/data-modeling/data-modeling_queries.html">Defining application queries</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/data-modeling/data-modeling_logical.html">Logical data modeling</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/data-modeling/data-modeling_physical.html">Physical data modeling</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/data-modeling/data-modeling_refining.html">Evaluating and refining data models</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/data-modeling/data-modeling_schema.html">Defining database schema</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/data-modeling/data-modeling_tools.html">Cassandra data modeling tools</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../developing/cql/index.html">Cassandra Query Language (CQL)</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/definitions.html">Definitions</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/types.html">Data types</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/ddl.html">Data definition (DDL)</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/dml.html">Data manipulation (DML)</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/dynamic-data-masking.html">Dynamic Data Masking (DDM)</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/operators.html">Operators</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../developing/cql/indexing/indexing-concepts.html">Indexing concepts</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../developing/cql/indexing/sai/sai-overview.html">SAI Overview</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="5"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/indexing/sai/sai-concepts.html">Concepts</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../getting-started/sai-quickstart.html">SAI Quickstart</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/indexing/sai/sai-faq.html">SAI FAQ</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/indexing/sai/sai-working-with.html">Working with SAI</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/indexing/sai/operations/sai-operations.html">SAI operations</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../developing/cql/indexing/2i/2i-overview.html">Secondary indexes (2i) overview</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="5"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/indexing/2i/2i-concepts.html">Concepts</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/indexing/2i/2i-working-with.html">Working with 2i</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/indexing/2i/operations/2i-build.html">Rebuild 2i</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/mvs.html">Materialized views</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/functions.html">Functions</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/json.html">JSON</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/security.html">Security</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/triggers.html">Triggers</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/appendices.html">Appendices</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/changes.html">Changes</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/SASI.html">SASI</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../developing/cql/cql_singlefile.html">Single file of CQL information</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../vector-search/overview.html">Vector Search overview</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../vector-search/concepts.html">Concepts</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../vector-search/data-modeling.html">Data Modeling</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../getting-started/vector-search-quickstart.html">Vector Search Quickstart</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../vector-search/vector-search-working-with.html">Working with Vector Search</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../managing/index.html">Managing</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../managing/configuration/index.html">Configuring</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/configuration/cass_yaml_file.html">cassandra.yaml</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/configuration/cass_rackdc_file.html">cassandra-rackdc.properties</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/configuration/cass_env_sh_file.html">cassandra-env.sh</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/configuration/cass_topo_file.html">cassandra-topologies.properties</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/configuration/cass_cl_archive_file.html">commitlog-archiving.properties</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/configuration/cass_logback_xml_file.html">logback.xml</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/configuration/cass_jvm_options_file.html">jvm-* files</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/configuration/configuration.html">Liberating cassandra.yaml Parameters' Names from Their Units</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../managing/operating/index.html">Operating</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/backups.html">Backups</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/bloom_filters.html">Bloom filters</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/bulk_loading.html">Bulk loading</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/cdc.html">Change Data Capture (CDC)</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/compaction/index.html">Compaction</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/compression.html">Compression</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/hardware.html">Hardware</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/hints.html">Hints</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../managing/operating/logging.html">Logging</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="5"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/auditlogging.html">Audit logging</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/audit_logging.html">Audit logging 2</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="5"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/fqllogging.html">Full query logging</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/metrics.html">Monitoring metrics</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/repair.html">Repair</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/read_repair.html">Read repair</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/security.html">Security</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/snitch.html">Snitches</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/topo_changes.html">Topology changes</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/transientreplication.html">Transient replication</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/operating/virtualtables.html">Virtual tables</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../managing/tools/index.html">Tools</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/tools/cqlsh.html">cqlsh: the CQL shell</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/tools/nodetool/nodetool.html">nodetool</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../managing/tools/sstable/index.html">SSTable tools</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="4"> |
| <span class="nav-line"> |
| <a class="nav-link" href="#cassandra:managing/tools/cassandra_stress.adoc">cassandra-stress</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../troubleshooting/index.html">Troubleshooting</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../troubleshooting/finding_nodes.html">Finding misbehaving nodes</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../troubleshooting/reading_logs.html">Reading Cassandra logs</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../troubleshooting/use_nodetool.html">Using nodetool</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../troubleshooting/use_tools.html">Using external tools to deep-dive</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../index.html">Reference</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="alter-table.html">ALTER TABLE</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="create-index.html">CREATE INDEX</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="create-custom-index.html">CREATE CUSTOM INDEX</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="create-table.html">CREATE TABLE</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="drop-index.html">DROP INDEX</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="drop-table.html">DROP TABLE</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../integrating/plugins/index.html">Plug-ins</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </div> |
| </nav> |
| <aside class="toc sidebar"> |
| <div class="toc-menu"></div> |
| </aside> |
| <main class="article default-main full-800" data-ceiling="topbar"> |
| <div class="article-banner"> |
| <p>You are viewing the documentation for a prerelease version.</p> |
| </div> |
| <div class="article-header"> |
| <nav class="crumbs" aria-label="breadcrumbs"> |
| <ul> |
| <li class="crumb"><a href="../../../index.html">Cassandra</a></li> |
| </ul> |
| </nav> |
| <div class="tools" role="navigation"> |
| <ul> |
| <li class="tool edit"><a href="https://github.com/apache/cassandra/edit/cassandra-5.0/doc/modules/cassandra/pages/reference/cql-commands/compact-subproperties.adoc" title="Edit Page" target="_blank" rel="noopener">Edit</a></li> |
| </ul> |
| </div> |
| </div> |
| <article class="doc"> |
| <div class="sect2"> |
| <h3 id="compaction-compaction_map"><a class="anchor" href="#compaction-compaction_map"></a>compaction = {compaction_map}</h3> |
| <div class="paragraph"> |
| <p>Defines the strategy for cleaning up data after writes.</p> |
| </div> |
| <div class="paragraph"> |
| <p>Syntax uses a simple JSON format:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="highlightjs highlight"><code class="language-language-cql hljs" data-lang="language-cql">compaction = { |
| 'class' : '<compaction_strategy_name>', |
| '<property_name>' : <value> [, ...] }</code></pre> |
| </div> |
| </div> |
| <div class="paragraph"> |
| <p>where the <compaction_strategy_name> is <a href="#UCS">UnifiedCompactionStrategy</a>, <a href="#STCS">SizeTieredCompactionStrategy</a>, <a href="#TWCS">TimeWindowCompactionStrategy</a>, or <a href="#LCS">LeveledCompactionStrategy</a>.</p> |
| </div> |
| <div class="admonitionblock important"> |
| <table> |
| <tr> |
| <td class="icon"> |
| <i class="fa icon-important" title="Important"></i> |
| </td> |
| <td class="content"> |
| <div class="paragraph"> |
| <p>Use only compaction implementations bundled with Apache Cassandra. |
| See <a href="../../managing/operating/compaction/index.html" class="page">Compaction Strategies</a> for more details.</p> |
| </div> |
| </td> |
| </tr> |
| </table> |
| </div> |
| <div class="sect3"> |
| <h4 id="common-properties"><a class="anchor" href="#common-properties"></a>Common properties</h4> |
| <div class="paragraph"> |
| <p>The following properties apply to all compaction strategies.</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="highlightjs highlight"><code class="language-language-cql hljs" data-lang="language-cql">compaction = { |
| 'class' : 'compaction_strategy_name', |
| 'enabled' : (true | false), |
| 'log_all' : (true | false), |
| 'only_purge_repaired_tombstone' : (true | false), |
| 'tombstone_threshold' : <ratio>, |
| 'tombstone_compaction_interval' : <sec>, |
| 'unchecked_tombstone_compaction' : (true | false) }</code></pre> |
| </div> |
| </div> |
| <div class="dlist"> |
| <dl> |
| <dt class="hdlist1">enabled</dt> |
| <dd> |
| <p>Enable background compaction.</p> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p><code>true</code> runs minor compactions</p> |
| </li> |
| <li> |
| <p><code>false</code> disables minor compactions</p> |
| </li> |
| </ul> |
| </div> |
| <div class="admonitionblock tip"> |
| <table> |
| <tr> |
| <td class="icon"> |
| <i class="fa icon-tip" title="Tip"></i> |
| </td> |
| <td class="content"> |
| <div class="paragraph"> |
| <p>Use <code>nodetool enableautocompaction</code> to start running compactions.</p> |
| </div> |
| </td> |
| </tr> |
| </table> |
| </div> |
| <div class="paragraph"> |
| <p>+ |
| Default: <code>true</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">log_all</dt> |
| <dd> |
| <p>Activates advanced logging for the entire cluster.</p> |
| <div class="paragraph"> |
| <p>Default: <code>false</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">only_purge_repaired_tombstone</dt> |
| <dd> |
| <p>Enabling this property prevents data from resurrecting when repair is not run within the <code>gc_grace_seconds</code>. |
| When its been a long time between repairs, the database keeps all tombstones.</p> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p><code>true</code> - Only allow tombstone purges on repaired SSTables.</p> |
| </li> |
| <li> |
| <p><code>false</code> - Purge tombstones on SSTables during compaction even if the table has not been repaired.</p> |
| </li> |
| </ul> |
| </div> |
| <div class="paragraph"> |
| <p>Default: <code>false</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">tombstone_threshold</dt> |
| <dd> |
| <p>The ratio of garbage-collectable tombstones to all contained columns. |
| If the ratio exceeds this limit, compactions starts only on that table to purge the tombstones.</p> |
| <div class="paragraph"> |
| <p>Default: <code>0.2</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">tombstone_compaction_interval</dt> |
| <dd> |
| <p>Number of seconds before compaction can run on an SSTable after it is created. |
| An SSTable is eligible for compaction when it exceeds the <code>tombstone_threshold</code>. |
| Because it might not be possible to drop tombstones when doing a single SSTable compaction, and since the compaction is triggered base on an estimated tombstone ratio, this setting makes the minimum interval between two single SSTable compactions tunable to prevent an SSTable from being constantly re-compacted.</p> |
| <div class="paragraph"> |
| <p>Default: <code>86400</code> (1 day)</p> |
| </div> |
| </dd> |
| <dt class="hdlist1">unchecked_tombstone_compaction</dt> |
| <dd> |
| <p>Setting to <code>true</code> allows tombstone compaction to run without pre-checking which tables are eligible for the operation. |
| Even without this pre-check, Apache Cassandra checks an SSTable to make sure it is safe to drop tombstones.</p> |
| <div class="paragraph"> |
| <p>Default: <code>false</code></p> |
| </div> |
| </dd> |
| </dl> |
| </div> |
| </div> |
| <div class="sect3"> |
| <h4 id="UCS"><a class="anchor" href="#UCS"></a>UnifiedCompactionStrategy</h4> |
| <div class="paragraph"> |
| <p>Unified Compaction Strategy is the recommended compaction strategy for most deployments. |
| The following properties only apply to UnifiedCompactionStrategy:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="highlightjs highlight"><code class="language-language-cql hljs" data-lang="language-cql">compaction = { |
| 'class' : 'UnifiedCompactionStrategy, |
| 'scaling_parameters' : list of scaling parameters, |
| 'target_sstable_size': <text>, |
| 'base_shard_count': <int> }</code></pre> |
| </div> |
| </div> |
| <div class="dlist"> |
| <dl> |
| <dt class="hdlist1">scaling_parameters</dt> |
| <dd> |
| <p>The maximum number of SSTables before a minor compaction is triggered.</p> |
| <div class="paragraph"> |
| <p>Default: <code>32</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">target_sstable_size</dt> |
| <dd> |
| <p>The target size for SSTables that use the UnifiedCompactionStrategy. |
| You must specify the bytes.</p> |
| <div class="paragraph"> |
| <p>Default: <code>1 GiB</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">base_shard_count</dt> |
| <dd> |
| <p>The minimum number of shards, used for levels with the smallest density.</p> |
| <div class="paragraph"> |
| <p>Default: <code>4</code> (1 for system tables, or when multiple data locations are defined)</p> |
| </div> |
| </dd> |
| <dt class="hdlist1">expired_sstable_check_frequency_seconds</dt> |
| <dd> |
| <p>Determines how often to check for expired SSTables.</p> |
| <div class="paragraph"> |
| <p>Default: <code>10 minutes</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">sstable_growth</dt> |
| <dd> |
| <p>The sstable growth component lambda, applied as a factor in the shard exponent calculation. |
| This is a number between 0 and 1 that controls what part of the density growth should apply to individual sstable size and what part should increase the number of shards. |
| Using a value of 1 has the effect of fixing the shard count to the base value. |
| Using 0.5 makes the shard count and sstable size grow with the square root of the density growth. |
| This is useful to decrease the sheer number of sstables that will be created for very large data sets. |
| For example, without growth correction a data set of 10TiB with 1GiB target size would result in over 10k sstables, which may present as too much overhead both as on-heap memory used by per-sstable structures as well as time to look for intersecting sstables and tracking overlapping sets during compaction. |
| Applying in this scenario (with base count 4) will reduce the potential number of sstables to ~160 of ~64GiB, which is still manageable both as memory overhead and individual compaction duration and space overhead. |
| The balance between the two can be further tweaked by increasing to get fewer but bigger sstables on the top level, and decreasing it to favour a higher count of smaller sstables. |
| The default value is 0.333 meaning the sstable size grows with the square root of the growth of the shard count.</p> |
| </dd> |
| </dl> |
| </div> |
| </div> |
| <div class="sect3"> |
| <h4 id="STCS"><a class="anchor" href="#STCS"></a>SizeTieredCompactionStrategy</h4> |
| <div class="paragraph"> |
| <p>The compaction class <code>SizeTieredCompactionStrategy</code> (STCS) triggers a minor compaction when table meets the <code>min_threshold</code>. |
| Minor compactions do not involve all the tables in a keyspace. |
| See <a href="../../managing/operating/compaction/stcs.html" class="page">SizeTieredCompactionStrategy (STCS)</a>.</p> |
| </div> |
| <div class="admonitionblock note"> |
| <table> |
| <tr> |
| <td class="icon"> |
| <i class="fa icon-note" title="Note"></i> |
| </td> |
| <td class="content"> |
| <div class="paragraph"> |
| <p>STCS is the default compaction strategy.</p> |
| </div> |
| </td> |
| </tr> |
| </table> |
| </div> |
| <div class="paragraph"> |
| <p>The following properties only apply to SizeTieredCompactionStrategy:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="highlightjs highlight"><code class="language-language-cql hljs" data-lang="language-cql">compaction = { |
| 'class' : 'SizeTieredCompactionStrategy', |
| 'bucket_high' : <factor>, |
| 'bucket_low' : <factor>, |
| 'min_sstable_size' : <int>, |
| 'min_threshold' : <int>, |
| 'max_threshold' : <int> }</code></pre> |
| </div> |
| </div> |
| <div class="dlist"> |
| <dl> |
| <dt class="hdlist1">min_threshold</dt> |
| <dd> |
| <p>The minimum number of SSTables to trigger a minor compaction.</p> |
| <div class="paragraph"> |
| <p><strong>Restriction:</strong> Not used in <code>LeveledCompactionStrategy</code>.</p> |
| </div> |
| <div class="paragraph"> |
| <p>Default: <code>4</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">max_threshold</dt> |
| <dd> |
| <p>The maximum number of SSTables before a minor compaction is triggered.</p> |
| <div class="paragraph"> |
| <p><strong>Restriction:</strong> Not used in <code>LeveledCompactionStrategy</code>.</p> |
| </div> |
| <div class="paragraph"> |
| <p>Default: <code>32</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">bucket_high</dt> |
| <dd> |
| <p>Size-tiered compaction merges sets of SSTables that are approximately the same size. |
| The database compares each SSTable size to the average of all SSTable sizes for this table on the node. |
| It merges SSTables whose size in KB are within [average-size * bucket_low] and [average-size * bucket_high].</p> |
| <div class="paragraph"> |
| <p>Default: <code>1.5</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">bucket_low</dt> |
| <dd> |
| <p>Size-tiered compaction merges sets of SSTables that are approximately the same size. |
| The database compares each SSTable size to the average of all SSTable sizes for this table on the node. |
| It merges SSTables whose size in KB are within [average-size * bucket_low] and [average-size * bucket_high].</p> |
| <div class="paragraph"> |
| <p>Default: <code>0.5</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">min_sstable_size</dt> |
| <dd> |
| <p>STCS groups SSTables into buckets. |
| The bucketing process groups SSTables that differ in size by less than 50%. |
| This bucketing process is too fine-grained for small SSTables. |
| If your SSTables are small, use this option to define a size threshold in MB below which all SSTables belong to one unique bucket.</p> |
| <div class="paragraph"> |
| <p>Default: <code>50</code> (MB)</p> |
| </div> |
| </dd> |
| </dl> |
| </div> |
| <div class="admonitionblock note"> |
| <table> |
| <tr> |
| <td class="icon"> |
| <i class="fa icon-note" title="Note"></i> |
| </td> |
| <td class="content"> |
| <div class="paragraph"> |
| <p>The <code>cold_reads_to_omit</code> property for <a href="../../managing/operating/compaction/stcs.html" class="page">SizeTieredCompactionStrategy (STCS)</a> is no longer supported.</p> |
| </div> |
| </td> |
| </tr> |
| </table> |
| </div> |
| </div> |
| <div class="sect3"> |
| <h4 id="LCS"><a class="anchor" href="#LCS"></a>LeveledCompactionStrategy</h4> |
| <div class="paragraph"> |
| <p>The compaction class <code>LeveledCompactionStrategy</code> (LCS) creates SSTables of a fixed, relatively small size (160 MB by default) that are grouped into levels. |
| Within each level, SSTables are guaranteed to be non-overlapping. |
| Each level (L0, L1, L2 and so on) is 10 times as large as the previous. |
| Disk I/O is more uniform and predictable on higher than on lower levels as SSTables are continuously being compacted into progressively larger levels. |
| At each level, row keys are merged into non-overlapping SSTables in the next level. |
| See <a href="../../managing/operating/compaction/lcs.html" class="page">LeveledCompactionStrategy (LCS)</a>.</p> |
| </div> |
| <div class="admonitionblock note"> |
| <table> |
| <tr> |
| <td class="icon"> |
| <i class="fa icon-note" title="Note"></i> |
| </td> |
| <td class="content"> |
| <div class="paragraph"> |
| <p>For more guidance, see <a href="https://www.datastax.com/dev/blog/when-to-use-leveled-compaction">When to Use Leveled Compaction</a> and <a href="https://www.datastax.com/dev/blog/leveled-compaction-in-apache-cassandra">Leveled Compaction</a> blog.</p> |
| </div> |
| </td> |
| </tr> |
| </table> |
| </div> |
| <div class="paragraph"> |
| <p>The following properties only apply to LeveledCompactionStrategy:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="highlightjs highlight"><code class="language-language-cql hljs" data-lang="language-cql">compaction = { |
| 'class' : 'LeveledCompactionStrategy, |
| 'sstable_size_in_mb' : <int> }</code></pre> |
| </div> |
| </div> |
| <div class="dlist"> |
| <dl> |
| <dt class="hdlist1">sstable_size_in_mb</dt> |
| <dd> |
| <p>The target size for SSTables that use the LeveledCompactionStrategy. |
| Although SSTable sizes should be less or equal to sstable_size_in_mb, it is possible that compaction could produce a larger SSTable during compaction. |
| This occurs when data for a given partition key is exceptionally large. |
| The Apache Cassandra database does not split the data into two SSTables.</p> |
| <div class="paragraph"> |
| <p>Default: <code>160</code></p> |
| </div> |
| <div class="admonitionblock caution"> |
| <table> |
| <tr> |
| <td class="icon"> |
| <i class="fa icon-caution" title="Caution"></i> |
| </td> |
| <td class="content"> |
| <div class="paragraph"> |
| <p>The default value, 160 MB, may be inefficient and negatively impact database indexing and the queries that rely on indexes. |
| For example, consider the benefit of using higher values for sstable_size_in_mb in tables that use (SAI) indexes. |
| For related information, see <a href="#developing:indexing/sai/configuring.adoc#saiConfigure__saiCompactionStrategies" class="page unresolved">Compaction strategies</a>.</p> |
| </div> |
| </td> |
| </tr> |
| </table> |
| </div> |
| </dd> |
| <dt class="hdlist1">fanout_size</dt> |
| <dd> |
| <p>The target size of levels increases by this <code>fanout_size</code> multiplier. |
| You can reduce the space amplification by tuning this option. |
| Default: 10</p> |
| </dd> |
| </dl> |
| </div> |
| </div> |
| <div class="sect3"> |
| <h4 id="TWCS"><a class="anchor" href="#TWCS"></a>TimeWindowCompactionStrategy</h4> |
| <div class="paragraph"> |
| <p>The compaction class <code>TimeWindowCompactionStrategy</code> (TWCS) compacts SSTables using a series of <em>time windows</em> or <em>buckets</em>. |
| TWCS creates a new time window within each successive time period. |
| During the active time window, TWCS compacts all SSTables flushed from memory into larger SSTables using STCS. |
| At the end of the time period, all of these SSTables are compacted into a single SSTable. |
| Then the next time window starts and the process repeats. |
| See <a href="../../managing/operating/compaction/twcs.html" class="page">TimeWindowCompactionStrategy (TWCS)</a>.</p> |
| </div> |
| <div class="admonitionblock note"> |
| <table> |
| <tr> |
| <td class="icon"> |
| <i class="fa icon-note" title="Note"></i> |
| </td> |
| <td class="content"> |
| <div class="paragraph"> |
| <p>All of the properties for STCS are also valid for TWCS.</p> |
| </div> |
| </td> |
| </tr> |
| </table> |
| </div> |
| <div class="paragraph"> |
| <p>The following properties apply only to TimeWindowCompactionStrategy:</p> |
| </div> |
| <div class="listingblock"> |
| <div class="content"> |
| <pre class="highlightjs highlight"><code class="language-language-cql hljs" data-lang="language-cql">compaction = { |
| 'class' : 'TimeWindowCompactionStrategy, |
| 'compaction_window_unit' : <days>, |
| 'compaction_window_size' : <int> }</code></pre> |
| </div> |
| </div> |
| <div class="dlist"> |
| <dl> |
| <dt class="hdlist1">compaction_window_unit</dt> |
| <dd> |
| <p>Time unit used to define the bucket size. |
| The value is based on the Java <code>TimeUnit</code>. |
| For the list of valid values, see the Java API <code>TimeUnit</code> page located at <a href="https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/TimeUnit.html" class="bare">docs.oracle.com/javase/8/docs/api/java/util/concurrent/TimeUnit.html</a>.</p> |
| <div class="paragraph"> |
| <p>Default: <code>days</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">compaction_window_size</dt> |
| <dd> |
| <p>Units per bucket.</p> |
| <div class="paragraph"> |
| <p>Default: <code>1</code></p> |
| </div> |
| </dd> |
| </dl> |
| </div> |
| </div> |
| <div class="sect3"> |
| <h4 id="datetieredcompactionstrategy-deprecated"><a class="anchor" href="#datetieredcompactionstrategy-deprecated"></a>DateTieredCompactionStrategy (deprecated)</h4> |
| <div class="admonitionblock important"> |
| <table> |
| <tr> |
| <td class="icon"> |
| <i class="fa icon-important" title="Important"></i> |
| </td> |
| <td class="content"> |
| <div class="paragraph"> |
| <p>Use <a href="#TWCS">TimeWindowCompactionStrategy</a> instead.</p> |
| </div> |
| </td> |
| </tr> |
| </table> |
| </div> |
| <div class="paragraph"> |
| <p>Stores data written within a certain period of time in the same SSTable.</p> |
| </div> |
| <div class="dlist"> |
| <dl> |
| <dt class="hdlist1">base_time_seconds</dt> |
| <dd> |
| <p>The size of the first time window.</p> |
| <div class="paragraph"> |
| <p>Default: <code>3600</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">max_sstable_age_days (deprecated)</dt> |
| <dd> |
| <p>Apache Cassandra does not compact SSTables if its most recent data is older than this property. |
| Fractional days can be set.</p> |
| <div class="paragraph"> |
| <p>Default: <code>1000</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">max_window_size_seconds</dt> |
| <dd> |
| <p>The maximum window size in seconds.</p> |
| <div class="paragraph"> |
| <p>Default: <code>86400</code></p> |
| </div> |
| </dd> |
| <dt class="hdlist1">timestamp_resolution</dt> |
| <dd> |
| <p>Units, <MICROSECONDS> or <MILLISECONDS>, to match the timestamp of inserted data.</p> |
| <div class="paragraph"> |
| <p>Default: <code>MICROSECONDS</code></p> |
| </div> |
| </dd> |
| </dl> |
| </div> |
| </div> |
| </div> |
| </article> |
| </main> |
| </div> |
| </div> |
| <footer class="grad grad--two flex-center pb-xlarge"> |
| <div class="inner text-center z2 relative"> |
| <h2 class="white py-small">Get started with Cassandra, fast.</h2> |
| <a id="footer-cta" href="/_/quickstart.html" class="btn btn--filled ma-medium">Quickstart Guide</a> |
| </div> |
| <div class="inner flex flex-distribute-items mt-xlarge z2 relative"> |
| <div class="col-2"> |
| <div id="footer-logo" class="logo logo--footer mb-medium"><img src="../../../../../assets/img/logo-white-r.png" alt="Cassandra Logo"></div> |
| <p>Apache Cassandra<img src="../../../../../assets/img/registered.svg" alt="®" style="width:18px;"> powers mission-critical deployments with improved performance and unparalleled levels of scale in the cloud.</p> |
| <div class="footer-social-icons"> |
| <a href="https://twitter.com/cassandra?lang=en" target="_blank"><img src="../../../../../assets/img/twitter-icon-circle-white.svg" alt="twitter icon" width="24"></a> |
| <a href="https://www.linkedin.com/company/apache-cassandra/" target="_blank"><img src="../../../../../assets/img/LI-In-Bug.png" alt="linked-in icon" width="24"></a> |
| <a href="https://www.youtube.com/c/PlanetCassandra" target="_blank"><img src="../../../../../assets/img/youtube-icon.png" alt="youtube icon" width="24"></a> |
| </div> |
| </div> |
| <div class="col-2 flex flex-center"> |
| <ul class="columns-2"> |
| <li class="mb-small"><a href="/">Home</a></li> |
| <li class="mb-small"><a href="/_/cassandra-basics.html">Cassandra Basics</a></li> |
| <li class="mb-small"><a href="/_/quickstart.html">Quickstart</a></li> |
| <li class="mb-small"><a href="/_/ecosystem.html">Ecosystem</a></li> |
| <li class="mb-small"><a href="/doc/latest/">Documentation</a></li> |
| <li class="mb-small"><a href="/_/community.html">Community</a></li> |
| <li class="mb-small"><a href="/_/case-studies.html">Case Studies</a></li> |
| <li class="mb-small"><a href="/_/resources.html">Resources</a></li> |
| <li class="mb-small"><a href="/_/blog.html">Blog</a></li> |
| </ul> |
| </div> |
| </div> |
| </footer> |
| <div class="lower-footer bg-white pa-medium"> |
| <div class="flex flex-row flex-vert-center"> |
| <div class="pr-medium"><img src="../../../../../assets/img//feather-small.png" alt="ASF" width="20"></div> |
| <div class="pr-medium"><a href="http://www.apache.org/" target="_blank">Foundation</a></div> |
| <div class="pr-medium"><a href="https://www.apache.org/events/current-event.html" target="_blank">Events</a></div> |
| <div class="pr-medium"><a href="https://www.apache.org/licenses/" target="_blank">License</a></div> |
| <div class="pr-medium"><a href="https://www.apache.org/foundation/thanks" target="_blank">Thanks</a></div> |
| <div class="pr-medium"><a href="https://www.apache.org/security" target="_blank">Security</a></div> |
| <div class="pr-medium"><a href="https://privacy.apache.org/policies/privacy-policy-public.html" target="_blank">Privacy</a></div> |
| <div class="pr-medium"><a href="https://www.apache.org/foundation/sponsorship" target="_blank">Sponsorship</a></div> |
| </div> |
| <p class="my-medium">© 2009-<script>document.write(new Date().getFullYear())</script> <a href="https://apache.org" target="_blank">The Apache Software Foundation</a> under the terms of the Apache License 2.0. Apache, the Apache feather logo, Apache Cassandra, Cassandra, and the Cassandra logo, are either registered trademarks or trademarks of The Apache Software Foundation.</p> |
| </div> |
| <div id="fade" class="hidden"></div> |
| <div id="modal" class="hidden"> |
| <div id="close-modal" class="cursor-pointer"><svg viewBox="0 0 24 24" width="24" height="24" stroke="currentColor" stroke-width="2" fill="none" stroke-linecap="round" stroke-linejoin="round" class="css-i6dzq1"><line x1="18" y1="6" x2="6" y2="18"></line><line x1="6" y1="6" x2="18" y2="18"></line></svg></div> |
| <div id="mod-content" class="vid-mod-content resp-container"></div> |
| </div> |
| <script src="../../../../../assets/js/site.js"></script> |
| <script async src="../../../../../assets/js/vendor/highlight.js"></script> |
| <script src="../../../../../assets/js/vendor/lunr.js"></script> |
| <script src="../../../../../assets/js/vendor/search.js" id="search-script" data-base-path="../../../../.." data-page-path="/Cassandra/5.0/cassandra/reference/cql-commands/compact-subproperties.html"></script> |
| <script async src="../../../../../assets/../search-index.js"></script> |
| <script> |
| jQuery(function(){ |
| var windowW = $(window).width(); |
| $(document) |
| .on('click','.mobile-nav-icon',function(){ |
| $('.main-nav').fadeIn(); |
| }) |
| .on('click','.main-nav',function(){ |
| if(windowW <= 1000){ |
| $(this).fadeOut(); |
| } |
| }) |
| .on('click','#version-toggle',function(){ |
| $(this).toggleClass('active'); |
| $(this).next().fadeToggle(); |
| }) |
| .on('click','#mobile-docs-nav-burger', function(){ |
| $(this).toggleClass('active'); |
| $('.docs-nav').toggleClass('active'); |
| }); |
| var url = window.location.pathname; |
| var isQuickstart = url.includes('quickstart.html'); |
| if(isQuickstart){ |
| var footerCTA = document.getElementById('footer-cta'); |
| footerCTA.innerHTML = 'Get latest updates'; |
| footerCTA.setAttribute('href', '/_/blog.html'); |
| } |
| }); |
| </script> |
| </div> |
| </body> |
| </html> |
