| |
| <!DOCTYPE html> |
| |
| |
| <html lang="en" data-content_root="../" data-theme="auto"> |
| |
| <head> |
| <meta charset="utf-8" /> |
| <meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="viewport" content="width=device-width, initial-scale=1" /> |
| |
| <title>Functions and table functions — Apache DataFusion in Python documentation</title> |
| |
| |
| |
| <script data-cfasync="false"> |
| document.documentElement.dataset.mode = localStorage.getItem("mode") || "auto"; |
| document.documentElement.dataset.theme = localStorage.getItem("theme") || "auto"; |
| </script> |
| <!-- |
| this give us a css class that will be invisible only if js is disabled |
| --> |
| <noscript> |
| <style> |
| .pst-js-only { display: none !important; } |
| |
| </style> |
| </noscript> |
| |
| <!-- Loaded before other Sphinx assets --> |
| <link href="../_static/styles/theme.css?digest=8878045cc6db502f8baf" rel="stylesheet" /> |
| <link href="../_static/styles/pydata-sphinx-theme.css?digest=8878045cc6db502f8baf" rel="stylesheet" /> |
| |
| <link rel="stylesheet" type="text/css" href="../_static/pygments.css?v=8f2a1f02" /> |
| <link rel="stylesheet" type="text/css" href="../_static/mystnb.11b39860a7a0cbfd473a3ad8a317855267ff0bd372690045ca344a6b62be495e.css" /> |
| <link rel="stylesheet" type="text/css" href="../_static/graphviz.css?v=4ae1632d" /> |
| <link rel="stylesheet" type="text/css" href="../_static/copybutton.css?v=76b2166b" /> |
| <link rel="stylesheet" type="text/css" href="../_static/theme_overrides.css?v=4af573bc" /> |
| |
| <!-- So that users can add custom icons --> |
| <script src="../_static/scripts/fontawesome.js?digest=8878045cc6db502f8baf"></script> |
| <!-- Pre-loaded scripts that we'll load fully later --> |
| <link rel="preload" as="script" href="../_static/scripts/bootstrap.js?digest=8878045cc6db502f8baf" /> |
| <link rel="preload" as="script" href="../_static/scripts/pydata-sphinx-theme.js?digest=8878045cc6db502f8baf" /> |
| |
| <script src="../_static/documentation_options.js?v=5929fcd5"></script> |
| <script src="../_static/doctools.js?v=9bcbadda"></script> |
| <script src="../_static/sphinx_highlight.js?v=dc90522c"></script> |
| <script src="../_static/clipboard.min.js?v=a7894cd8"></script> |
| <script src="../_static/copybutton.js?v=f281be69"></script> |
| <script>DOCUMENTATION_OPTIONS.pagename = 'extension-guide/functions';</script> |
| <script src="../_static/toc-toggle.js?v=36375f01"></script> |
| <link rel="icon" href="../_static/favicon.svg"/> |
| <link rel="index" title="Index" href="../genindex.html" /> |
| <link rel="search" title="Search" href="../search.html" /> |
| <link rel="next" title="Extension codecs" href="codecs.html" /> |
| <link rel="prev" title="Providers and catalogs" href="table-providers.html" /> |
| <meta name="viewport" content="width=device-width, initial-scale=1"/> |
| <meta name="docsearch:language" content="en"/> |
| <meta name="docsearch:version" content="" /> |
| </head> |
| |
| |
| <body data-bs-spy="scroll" data-bs-target=".bd-toc-nav" data-offset="180" data-bs-root-margin="0px 0px -60%" data-default-mode="auto"> |
| |
| |
| |
| <div id="pst-skip-link" class="skip-link d-print-none"><a href="#main-content">Skip to main content</a></div> |
| |
| <div id="pst-scroll-pixel-helper"></div> |
| |
| <button type="button" class="btn rounded-pill" id="pst-back-to-top"> |
| <i class="fa-solid fa-arrow-up"></i>Back to top</button> |
| |
| |
| <dialog id="pst-search-dialog"> |
| |
| <form class="bd-search d-flex align-items-center" |
| action="../search.html" |
| method="get"> |
| <i class="fa-solid fa-magnifying-glass"></i> |
| <input type="search" |
| class="form-control" |
| name="q" |
| placeholder="Search the docs ..." |
| aria-label="Search the docs ..." |
| autocomplete="off" |
| autocorrect="off" |
| autocapitalize="off" |
| spellcheck="false"/> |
| <span class="search-button__kbd-shortcut"><kbd class="kbd-shortcut__modifier">Ctrl</kbd>+<kbd>K</kbd></span> |
| </form> |
| </dialog> |
| |
| <div class="pst-async-banner-revealer d-none"> |
| <aside id="bd-header-version-warning" class="d-none d-print-none" aria-label="Version warning"></aside> |
| </div> |
| |
| |
| <header class="bd-header navbar navbar-expand-lg bd-navbar d-print-none"> |
| <div class="bd-header__inner bd-page-width"> |
| <button class="pst-navbar-icon sidebar-toggle primary-toggle" aria-label="Site navigation"> |
| <span class="fa-solid fa-bars"></span> |
| </button> |
| |
| |
| <div class="col-lg-3 navbar-header-items__start"> |
| |
| <div class="navbar-item"> |
| |
| |
| |
| |
| |
| <a class="navbar-brand logo" href="../index.html"> |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| |
| <img src="../_static/original.svg" class="logo__image only-light" alt="Apache DataFusion in Python"/> |
| <img src="../_static/original_dark.svg" class="logo__image only-dark pst-js-only" alt="Apache DataFusion in Python"/> |
| |
| |
| </a></div> |
| |
| </div> |
| |
| <div class="col-lg-9 navbar-header-items"> |
| |
| <div class="me-auto navbar-header-items__center"> |
| |
| <div class="navbar-item"> |
| <nav> |
| <ul class="bd-navbar-elements navbar-nav"> |
| |
| <li class="nav-item "> |
| <a class="nav-link nav-internal" href="../user-guide/index.html"> |
| User Guide |
| </a> |
| </li> |
| |
| |
| <li class="nav-item current active"> |
| <a class="nav-link nav-internal" href="index.html"> |
| Extension Guide |
| </a> |
| </li> |
| |
| |
| <li class="nav-item "> |
| <a class="nav-link nav-internal" href="../contributor-guide/index.html"> |
| Contributor Guide |
| </a> |
| </li> |
| |
| |
| <li class="nav-item "> |
| <a class="nav-link nav-internal" href="../autoapi/index.html"> |
| API Reference |
| </a> |
| </li> |
| |
| |
| <li class="nav-item "> |
| <a class="nav-link nav-internal" href="../links.html"> |
| Links |
| </a> |
| </li> |
| |
| </ul> |
| </nav></div> |
| |
| </div> |
| |
| |
| <div class="navbar-header-items__end"> |
| |
| <div class="navbar-item navbar-persistent--container"> |
| |
| |
| <button class="btn search-button-field search-button__button pst-js-only" title="Search" aria-label="Search" data-bs-placement="bottom" data-bs-toggle="tooltip"> |
| <i class="fa-solid fa-magnifying-glass"></i> |
| <span class="search-button__default-text">Search</span> |
| <span class="search-button__kbd-shortcut"><kbd class="kbd-shortcut__modifier">Ctrl</kbd>+<kbd class="kbd-shortcut__modifier">K</kbd></span> |
| </button> |
| </div> |
| |
| |
| <div class="navbar-item"><ul class="navbar-icon-links" |
| aria-label="Icon Links"> |
| <li class="nav-item"> |
| |
| |
| |
| |
| |
| |
| |
| |
| <a href="https://github.com/apache/datafusion-python" title="GitHub" class="nav-link pst-navbar-icon" rel="noopener" target="_blank" data-bs-toggle="tooltip" data-bs-placement="bottom"><i class="fa-brands fa-github fa-lg" aria-hidden="true"></i> |
| <span class="sr-only">GitHub</span></a> |
| </li> |
| <li class="nav-item"> |
| |
| |
| |
| |
| |
| |
| |
| |
| <a href="https://docs.rs/datafusion/latest/datafusion/" title="Rust API docs (docs.rs)" class="nav-link pst-navbar-icon" rel="noopener" target="_blank" data-bs-toggle="tooltip" data-bs-placement="bottom"><i class="fa-brands fa-rust fa-lg" aria-hidden="true"></i> |
| <span class="sr-only">Rust API docs (docs.rs)</span></a> |
| </li> |
| </ul></div> |
| |
| <div class="navbar-item"> |
| |
| <button class="btn btn-sm nav-link pst-navbar-icon theme-switch-button pst-js-only" aria-label="Color mode" data-bs-title="Color mode" data-bs-placement="bottom" data-bs-toggle="tooltip"> |
| <i class="theme-switch fa-solid fa-sun fa-lg" data-mode="light" title="Light"></i> |
| <i class="theme-switch fa-solid fa-moon fa-lg" data-mode="dark" title="Dark"></i> |
| <i class="theme-switch fa-solid fa-circle-half-stroke fa-lg" data-mode="auto" title="System Settings"></i> |
| </button></div> |
| |
| </div> |
| |
| </div> |
| |
| |
| <div class="navbar-persistent--mobile"> |
| |
| <button class="btn search-button-field search-button__button pst-js-only" title="Search" aria-label="Search" data-bs-placement="bottom" data-bs-toggle="tooltip"> |
| <i class="fa-solid fa-magnifying-glass"></i> |
| <span class="search-button__default-text">Search</span> |
| <span class="search-button__kbd-shortcut"><kbd class="kbd-shortcut__modifier">Ctrl</kbd>+<kbd class="kbd-shortcut__modifier">K</kbd></span> |
| </button> |
| </div> |
| |
| |
| |
| <button class="pst-navbar-icon sidebar-toggle secondary-toggle" aria-label="On this page"> |
| <span class="fa-solid fa-outdent"></span> |
| </button> |
| |
| </div> |
| |
| </header> |
| |
| |
| <div class="bd-container"> |
| <div class="bd-container__inner bd-page-width"> |
| |
| |
| |
| <dialog id="pst-primary-sidebar-modal"></dialog> |
| <div id="pst-primary-sidebar" class="bd-sidebar-primary bd-sidebar"> |
| |
| |
| |
| <div class="sidebar-header-items sidebar-primary__section"> |
| |
| |
| <div class="sidebar-header-items__center"> |
| |
| |
| |
| <div class="navbar-item"> |
| <nav> |
| <ul class="bd-navbar-elements navbar-nav"> |
| |
| <li class="nav-item "> |
| <a class="nav-link nav-internal" href="../user-guide/index.html"> |
| User Guide |
| </a> |
| </li> |
| |
| |
| <li class="nav-item current active"> |
| <a class="nav-link nav-internal" href="index.html"> |
| Extension Guide |
| </a> |
| </li> |
| |
| |
| <li class="nav-item "> |
| <a class="nav-link nav-internal" href="../contributor-guide/index.html"> |
| Contributor Guide |
| </a> |
| </li> |
| |
| |
| <li class="nav-item "> |
| <a class="nav-link nav-internal" href="../autoapi/index.html"> |
| API Reference |
| </a> |
| </li> |
| |
| |
| <li class="nav-item "> |
| <a class="nav-link nav-internal" href="../links.html"> |
| Links |
| </a> |
| </li> |
| |
| </ul> |
| </nav></div> |
| |
| |
| </div> |
| |
| |
| |
| <div class="sidebar-header-items__end"> |
| |
| <div class="navbar-item"><ul class="navbar-icon-links" |
| aria-label="Icon Links"> |
| <li class="nav-item"> |
| |
| |
| |
| |
| |
| |
| |
| |
| <a href="https://github.com/apache/datafusion-python" title="GitHub" class="nav-link pst-navbar-icon" rel="noopener" target="_blank" data-bs-toggle="tooltip" data-bs-placement="bottom"><i class="fa-brands fa-github fa-lg" aria-hidden="true"></i> |
| <span class="sr-only">GitHub</span></a> |
| </li> |
| <li class="nav-item"> |
| |
| |
| |
| |
| |
| |
| |
| |
| <a href="https://docs.rs/datafusion/latest/datafusion/" title="Rust API docs (docs.rs)" class="nav-link pst-navbar-icon" rel="noopener" target="_blank" data-bs-toggle="tooltip" data-bs-placement="bottom"><i class="fa-brands fa-rust fa-lg" aria-hidden="true"></i> |
| <span class="sr-only">Rust API docs (docs.rs)</span></a> |
| </li> |
| </ul></div> |
| |
| <div class="navbar-item"> |
| |
| <button class="btn btn-sm nav-link pst-navbar-icon theme-switch-button pst-js-only" aria-label="Color mode" data-bs-title="Color mode" data-bs-placement="bottom" data-bs-toggle="tooltip"> |
| <i class="theme-switch fa-solid fa-sun fa-lg" data-mode="light" title="Light"></i> |
| <i class="theme-switch fa-solid fa-moon fa-lg" data-mode="dark" title="Dark"></i> |
| <i class="theme-switch fa-solid fa-circle-half-stroke fa-lg" data-mode="auto" title="System Settings"></i> |
| </button></div> |
| |
| </div> |
| |
| </div> |
| |
| <div class="sidebar-primary-items__start sidebar-primary__section"> |
| <div class="sidebar-primary-item"> |
| <nav class="bd-docs-nav bd-links" aria-label="Section Navigation"> |
| <p class="bd-links__title" role="heading" aria-level="1">Section Navigation</p> |
| <div class="bd-toc-item navbar-nav"> |
| <ul class="current nav bd-sidenav"> |
| <li class="toctree-l1 has-children"><a class="reference internal" href="../user-guide/index.html">User Guide</a><details open="open"><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../user-guide/introduction.html">Introduction</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../user-guide/basics.html">Concepts</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../user-guide/data-sources.html">Data Sources</a></li> |
| |
| <li class="toctree-l2 has-children"><a class="reference internal" href="../user-guide/dataframe/index.html">DataFrames</a><details><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/dataframe/rendering.html">DataFrame Rendering</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/dataframe/execution-metrics.html">Execution Metrics</a></li> |
| </ul> |
| </details></li> |
| <li class="toctree-l2 has-children"><a class="reference internal" href="../user-guide/common-operations/index.html">Common Operations</a><details><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/common-operations/views.html">Registering Views</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/common-operations/basic-info.html">Basic Operations</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/common-operations/select-and-filter.html">Column Selections</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/common-operations/expressions.html">Expressions</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/common-operations/joins.html">Joins</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/common-operations/functions.html">Functions</a></li> |
| |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/common-operations/spark-functions.html">Spark-Compatible Functions</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/common-operations/aggregations.html">Aggregation</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/common-operations/windows.html">Window Functions</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/common-operations/udf-and-udfa.html">User-Defined Functions</a></li> |
| </ul> |
| </details></li> |
| <li class="toctree-l2 has-children"><a class="reference internal" href="../user-guide/io/index.html">IO</a><details><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/io/arrow.html">Arrow</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/io/avro.html">Avro</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/io/csv.html">CSV</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/io/json.html">JSON</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/io/parquet.html">Parquet</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/io/table_provider.html">Custom Table Provider</a></li> |
| </ul> |
| </details></li> |
| <li class="toctree-l2"><a class="reference internal" href="../user-guide/configuration.html">Configuration</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../user-guide/extensions.html">Using extension libraries</a></li> |
| <li class="toctree-l2 has-children"><a class="reference internal" href="../user-guide/distributing-work/index.html">Distributing work</a><details><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/distributing-work/expressions.html">Shipping expressions to workers</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../user-guide/distributing-work/query-engines.html">Distributed query engines</a></li> |
| </ul> |
| </details></li> |
| <li class="toctree-l2"><a class="reference internal" href="../user-guide/sql.html">SQL</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../user-guide/upgrade-guides.html">Upgrade Guides</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../user-guide/ai-coding-assistants.html">Using AI Coding Assistants</a></li> |
| </ul> |
| </details></li> |
| <li class="toctree-l1 current active has-children"><a class="reference internal" href="index.html">Extension Guide</a><details open="open"><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul class="current"> |
| <li class="toctree-l2"><a class="reference internal" href="why-ffi.html">Why FFI</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="capsule-protocol.html">The capsule protocol</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="table-providers.html">Providers and catalogs</a></li> |
| <li class="toctree-l2 current active"><a class="current reference internal" href="#">Functions and table functions</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="codecs.html">Extension codecs</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="bundles.html">Extension bundles</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="query-planners.html">Query planners</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="other-components.html">Optimizer rules and configuration</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="sessions.html">Sessions, handles, and lifetimes</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="checklist.html">Extension author checklist</a></li> |
| </ul> |
| </details></li> |
| <li class="toctree-l1 has-children"><a class="reference internal" href="../contributor-guide/index.html">Contributor Guide</a><details open="open"><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul> |
| <li class="toctree-l2"><a class="reference internal" href="../contributor-guide/introduction.html">Introduction</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../contributor-guide/pyo3-guidelines.html">PyO3 binding guidelines</a></li> |
| <li class="toctree-l2"><a class="reference internal" href="../contributor-guide/ffi-internals.html">FFI framing internals</a></li> |
| </ul> |
| </details></li> |
| <li class="toctree-l1 has-children"><a class="reference internal" href="../autoapi/index.html">API Reference</a><details open="open"><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul> |
| <li class="toctree-l2 has-children"><a class="reference internal" href="../autoapi/datafusion/index.html">datafusion</a><details><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/catalog/index.html">datafusion.catalog</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/context/index.html">datafusion.context</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/dataframe/index.html">datafusion.dataframe</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/dataframe_formatter/index.html">datafusion.dataframe_formatter</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/expr/index.html">datafusion.expr</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/extensions/index.html">datafusion.extensions</a></li> |
| <li class="toctree-l3 has-children"><a class="reference internal" href="../autoapi/datafusion/functions/index.html">datafusion.functions</a><details><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul> |
| <li class="toctree-l4"><a class="reference internal" href="../autoapi/datafusion/functions/spark/index.html">datafusion.functions.spark</a></li> |
| </ul> |
| </details></li> |
| <li class="toctree-l3 has-children"><a class="reference internal" href="../autoapi/datafusion/input/index.html">datafusion.input</a><details><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul> |
| <li class="toctree-l4"><a class="reference internal" href="../autoapi/datafusion/input/base/index.html">datafusion.input.base</a></li> |
| <li class="toctree-l4"><a class="reference internal" href="../autoapi/datafusion/input/location/index.html">datafusion.input.location</a></li> |
| </ul> |
| </details></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/io/index.html">datafusion.io</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/ipc/index.html">datafusion.ipc</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/object_store/index.html">datafusion.object_store</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/options/index.html">datafusion.options</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/plan/index.html">datafusion.plan</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/record_batch/index.html">datafusion.record_batch</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/substrait/index.html">datafusion.substrait</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/unparser/index.html">datafusion.unparser</a></li> |
| <li class="toctree-l3"><a class="reference internal" href="../autoapi/datafusion/user_defined/index.html">datafusion.user_defined</a></li> |
| </ul> |
| </details></li> |
| </ul> |
| </details></li> |
| <li class="toctree-l1 has-children"><a class="reference internal" href="../links.html">Links</a><details open="open"><summary><span class="toctree-toggle" role="presentation"><i class="fa-solid fa-chevron-down"></i></span></summary><ul> |
| <li class="toctree-l2"><a class="reference external" href="https://github.com/apache/datafusion-python">GitHub and Issue Tracker</a></li> |
| <li class="toctree-l2"><a class="reference external" href="https://docs.rs/datafusion/latest/datafusion/">Rust API Docs</a></li> |
| <li class="toctree-l2"><a class="reference external" href="https://github.com/apache/datafusion/blob/main/CODE_OF_CONDUCT.md">Code of Conduct</a></li> |
| <li class="toctree-l2"><a class="reference external" href="https://github.com/apache/datafusion-python/tree/main/examples">Examples</a></li> |
| </ul> |
| </details></li> |
| </ul> |
| </div> |
| </nav></div> |
| </div> |
| |
| |
| <div class="sidebar-primary-items__end sidebar-primary__section"> |
| <div class="sidebar-primary-item"> |
| <div id="ethical-ad-placement" |
| class="flat" |
| data-ea-publisher="readthedocs" |
| data-ea-type="readthedocs-sidebar" |
| data-ea-manual="true"> |
| </div></div> |
| </div> |
| |
| |
| </div> |
| |
| <main id="main-content" class="bd-main" role="main"> |
| |
| |
| <div class="bd-content"> |
| <div class="bd-article-container"> |
| |
| <div class="bd-header-article d-print-none"> |
| <div class="header-article-items header-article__inner"> |
| |
| <div class="header-article-items__start"> |
| |
| <div class="header-article-item"> |
| |
| <nav aria-label="Breadcrumb" class="d-print-none"> |
| <ul class="bd-breadcrumbs"> |
| |
| <li class="breadcrumb-item breadcrumb-home"> |
| <a href="../index.html" class="nav-link" aria-label="Home"> |
| <i class="fa-solid fa-home"></i> |
| </a> |
| </li> |
| |
| <li class="breadcrumb-item"><a href="index.html" class="nav-link">Extension Guide</a></li> |
| |
| <li class="breadcrumb-item active" aria-current="page"><span class="ellipsis">Functions and table functions</span></li> |
| </ul> |
| </nav> |
| </div> |
| |
| </div> |
| |
| |
| </div> |
| </div> |
| |
| |
| |
| |
| <div id="searchbox"></div> |
| <article class="bd-article"> |
| |
| <!--- |
| Licensed to the Apache Software Foundation (ASF) under one |
| or more contributor license agreements. See the NOTICE file |
| distributed with this work for additional information |
| regarding copyright ownership. The ASF licenses this file |
| to you under the Apache License, Version 2.0 (the |
| "License"); you may not use this file except in compliance |
| with the License. You may obtain a copy of the License at |
| |
| http://www.apache.org/licenses/LICENSE-2.0 |
| |
| Unless required by applicable law or agreed to in writing, |
| software distributed under the License is distributed on an |
| "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| KIND, either express or implied. See the License for the |
| specific language governing permissions and limitations |
| under the License. |
| --> |
| <section id="functions-and-table-functions"> |
| <span id="extension-functions"></span><h1>Functions and table functions<a class="headerlink" href="#functions-and-table-functions" title="Link to this heading">#</a></h1> |
| <p>Four hooks contribute functions written in Rust. Users can also define |
| functions in pure Python — see |
| <a class="reference internal" href="../user-guide/common-operations/udf-and-udfa.html"><span class="doc">User-Defined Functions</span></a> — and the two roads meet at |
| the same registration methods.</p> |
| <div class="pst-scrollable-table-container"><table class="table"> |
| <thead> |
| <tr class="row-odd"><th class="head"><p>Hook</p></th> |
| <th class="head"><p>Contributes</p></th> |
| <th class="head"><p>Wrapped by</p></th> |
| <th class="head"><p>Registered with</p></th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">__datafusion_scalar_udf__</span></code></p></td> |
| <td><p>scalar function</p></td> |
| <td><p><code class="xref py py-func docutils literal notranslate"><span class="pre">datafusion.udf()</span></code></p></td> |
| <td><p><code class="xref py py-meth docutils literal notranslate"><span class="pre">register_udf()</span></code></p></td> |
| </tr> |
| <tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">__datafusion_aggregate_udf__</span></code></p></td> |
| <td><p>aggregate function</p></td> |
| <td><p><code class="xref py py-func docutils literal notranslate"><span class="pre">datafusion.udaf()</span></code></p></td> |
| <td><p><code class="xref py py-meth docutils literal notranslate"><span class="pre">register_udaf()</span></code></p></td> |
| </tr> |
| <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">__datafusion_window_udf__</span></code></p></td> |
| <td><p>window function</p></td> |
| <td><p><code class="xref py py-func docutils literal notranslate"><span class="pre">datafusion.udwf()</span></code></p></td> |
| <td><p><code class="xref py py-meth docutils literal notranslate"><span class="pre">register_udwf()</span></code></p></td> |
| </tr> |
| <tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">__datafusion_table_function__</span></code></p></td> |
| <td><p>function returning a table</p></td> |
| <td><p><code class="xref py py-func docutils literal notranslate"><span class="pre">datafusion.udtf()</span></code></p></td> |
| <td><p><code class="xref py py-meth docutils literal notranslate"><span class="pre">register_udtf()</span></code></p></td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <p>All four are implemented in <a class="reference external" href="https://github.com/apache/datafusion-python/tree/main/examples/datafusion-ffi-example"><code class="docutils literal notranslate"><span class="pre">datafusion-ffi-example</span></code></a>, one per file.</p> |
| <section id="the-three-scalar-shaped-hooks"> |
| <h2>The three scalar-shaped hooks<a class="headerlink" href="#the-three-scalar-shaped-hooks" title="Link to this heading">#</a></h2> |
| <p>The scalar, aggregate, and window getters take <strong>no argument</strong> beyond <code class="docutils literal notranslate"><span class="pre">py</span></code> — |
| they need no codec and no task-context provider, because a function is |
| identified by name and signature rather than by anything session-scoped:</p> |
| <div class="highlight-rust notranslate"><div class="highlight"><pre><span></span><span class="cp">#[pymethods]</span> |
| <span class="k">impl</span><span class="w"> </span><span class="n">MyScalarUDF</span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="k">fn</span><span class="w"> </span><span class="nf">__datafusion_scalar_udf__</span><span class="o"><'</span><span class="na">py</span><span class="o">></span><span class="p">(</span> |
| <span class="w"> </span><span class="o">&</span><span class="bp">self</span><span class="p">,</span> |
| <span class="w"> </span><span class="n">py</span><span class="p">:</span><span class="w"> </span><span class="nc">Python</span><span class="o"><'</span><span class="na">py</span><span class="o">></span><span class="p">,</span> |
| <span class="w"> </span><span class="p">)</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="nc">PyResult</span><span class="o"><</span><span class="n">Bound</span><span class="o"><'</span><span class="na">py</span><span class="p">,</span><span class="w"> </span><span class="n">PyCapsule</span><span class="o">>></span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="kd">let</span><span class="w"> </span><span class="n">udf</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">Arc</span><span class="p">::</span><span class="n">new</span><span class="p">(</span><span class="n">ScalarUDF</span><span class="p">::</span><span class="n">from</span><span class="p">(</span><span class="bp">self</span><span class="p">.</span><span class="n">clone</span><span class="p">()));</span> |
| <span class="w"> </span><span class="kd">let</span><span class="w"> </span><span class="n">ffi</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">FFI_ScalarUDF</span><span class="p">::</span><span class="n">from</span><span class="p">(</span><span class="n">udf</span><span class="p">);</span> |
| |
| <span class="w"> </span><span class="n">PyCapsule</span><span class="p">::</span><span class="n">new_with_value</span><span class="p">(</span><span class="n">py</span><span class="p">,</span><span class="w"> </span><span class="n">ffi</span><span class="p">,</span><span class="w"> </span><span class="n">cr</span><span class="s">"datafusion_scalar_udf"</span><span class="p">)</span> |
| <span class="w"> </span><span class="p">}</span> |
| <span class="p">}</span> |
| </pre></div> |
| </div> |
| <p>Aggregate and window follow identically with <code class="docutils literal notranslate"><span class="pre">FFI_AggregateUDF</span></code> / |
| <code class="docutils literal notranslate"><span class="pre">FFI_WindowUDF</span></code> and the matching capsule names.</p> |
| <p>Your users wrap the object once and register the result:</p> |
| <div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span><span class="w"> </span><span class="nn">datafusion</span><span class="w"> </span><span class="kn">import</span> <span class="n">udf</span> |
| |
| <span class="n">ctx</span><span class="o">.</span><span class="n">register_udf</span><span class="p">(</span><span class="n">udf</span><span class="p">(</span><span class="n">my_library</span><span class="o">.</span><span class="n">MyScalarUDF</span><span class="p">()))</span> |
| </pre></div> |
| </div> |
| </section> |
| <section id="table-functions"> |
| <h2>Table functions<a class="headerlink" href="#table-functions" title="Link to this heading">#</a></h2> |
| <p>A table function takes literal <code class="docutils literal notranslate"><span class="pre">Expr</span></code> arguments and returns a table provider, |
| so it needs the host’s logical codec the way a |
| <a class="reference internal" href="table-providers.html#extension-providers"><span class="std std-ref">table provider</span></a> does:</p> |
| <div class="highlight-rust notranslate"><div class="highlight"><pre><span></span><span class="k">fn</span><span class="w"> </span><span class="nf">__datafusion_table_function__</span><span class="o"><'</span><span class="na">py</span><span class="o">></span><span class="p">(</span> |
| <span class="w"> </span><span class="o">&</span><span class="bp">self</span><span class="p">,</span> |
| <span class="w"> </span><span class="n">py</span><span class="p">:</span><span class="w"> </span><span class="nc">Python</span><span class="o"><'</span><span class="na">py</span><span class="o">></span><span class="p">,</span> |
| <span class="w"> </span><span class="n">session</span><span class="p">:</span><span class="w"> </span><span class="nc">Bound</span><span class="o"><'</span><span class="na">py</span><span class="p">,</span><span class="w"> </span><span class="n">PyAny</span><span class="o">></span><span class="p">,</span> |
| <span class="p">)</span><span class="w"> </span><span class="p">-></span><span class="w"> </span><span class="nc">PyResult</span><span class="o"><</span><span class="n">Bound</span><span class="o"><'</span><span class="na">py</span><span class="p">,</span><span class="w"> </span><span class="n">PyCapsule</span><span class="o">>></span><span class="w"> </span><span class="p">{</span> |
| <span class="w"> </span><span class="kd">let</span><span class="w"> </span><span class="n">func</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="bp">self</span><span class="p">.</span><span class="n">clone</span><span class="p">();</span> |
| <span class="w"> </span><span class="kd">let</span><span class="w"> </span><span class="n">codec</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">ffi_logical_codec_from_pycapsule</span><span class="p">(</span><span class="n">session</span><span class="p">,</span><span class="w"> </span><span class="nb">None</span><span class="p">)</span><span class="o">?</span><span class="p">;</span> |
| <span class="w"> </span><span class="kd">let</span><span class="w"> </span><span class="n">provider</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">FFI_TableFunction</span><span class="p">::</span><span class="n">new_with_ffi_codec</span><span class="p">(</span><span class="n">Arc</span><span class="p">::</span><span class="n">new</span><span class="p">(</span><span class="n">func</span><span class="p">),</span><span class="w"> </span><span class="nb">None</span><span class="p">,</span><span class="w"> </span><span class="n">codec</span><span class="p">);</span> |
| |
| <span class="w"> </span><span class="n">PyCapsule</span><span class="p">::</span><span class="n">new_with_value</span><span class="p">(</span><span class="n">py</span><span class="p">,</span><span class="w"> </span><span class="n">provider</span><span class="p">,</span><span class="w"> </span><span class="n">cr</span><span class="s">"datafusion_table_function"</span><span class="p">)</span> |
| <span class="p">}</span> |
| </pre></div> |
| </div> |
| <p>Only literal expressions are supported as arguments. The Python side is |
| described under |
| <a class="reference internal" href="../user-guide/common-operations/udf-and-udfa.html"><span class="doc">Table Functions</span></a>.</p> |
| </section> |
| <section id="serializing-functions"> |
| <h2>Serializing functions<a class="headerlink" href="#serializing-functions" title="Link to this heading">#</a></h2> |
| <p>A function that appears in a plan leaving the process has to be reconstructible |
| on the far side. Functions are the one case where a codec often needs <strong>no |
| payload at all</strong>: the name is the whole encoding, <code class="docutils literal notranslate"><span class="pre">try_encode_udf</span></code> writes |
| nothing, and <code class="docutils literal notranslate"><span class="pre">try_decode_udf</span></code> rebuilds the function from <code class="docutils literal notranslate"><span class="pre">name</span></code>. See |
| <a class="reference internal" href="codecs.html#extension-codecs"><span class="std std-ref">Extension codecs</span></a> for how that works and for the one obligation it puts |
| on your decoder — with an empty payload there is no id to route on, so your |
| <code class="docutils literal notranslate"><span class="pre">try_decode_udf</span></code> can be called with a <code class="docutils literal notranslate"><span class="pre">name</span></code> belonging to another library.</p> |
| <p><code class="docutils literal notranslate"><span class="pre">NameOnlyUdfCodec</span></code> in <a class="reference external" href="https://github.com/apache/datafusion-python/tree/main/examples/datafusion-ffi-example"><code class="docutils literal notranslate"><span class="pre">datafusion-ffi-example</span></code></a> is the worked case.</p> |
| </section> |
| </section> |
| |
| |
| </article> |
| |
| |
| |
| |
| |
| <footer class="prev-next-footer d-print-none"> |
| |
| <div class="prev-next-area"> |
| <a class="left-prev" |
| href="table-providers.html" |
| title="previous page"> |
| <i class="fa-solid fa-angle-left"></i> |
| <div class="prev-next-info"> |
| <p class="prev-next-subtitle">previous</p> |
| <p class="prev-next-title">Providers and catalogs</p> |
| </div> |
| </a> |
| <a class="right-next" |
| href="codecs.html" |
| title="next page"> |
| <div class="prev-next-info"> |
| <p class="prev-next-subtitle">next</p> |
| <p class="prev-next-title">Extension codecs</p> |
| </div> |
| <i class="fa-solid fa-angle-right"></i> |
| </a> |
| </div> |
| </footer> |
| |
| </div> |
| |
| |
| |
| <dialog id="pst-secondary-sidebar-modal"></dialog> |
| <div id="pst-secondary-sidebar" class="bd-sidebar-secondary bd-toc"><div class="sidebar-secondary-items sidebar-secondary__inner"> |
| |
| |
| <div class="sidebar-secondary-item"> |
| <div |
| id="pst-page-navigation-heading-2" |
| class="page-toc tocsection onthispage"> |
| <i class="fa-solid fa-list"></i> On this page |
| </div> |
| <nav class="bd-toc-nav page-toc" aria-labelledby="pst-page-navigation-heading-2"> |
| <ul class="visible nav section-nav flex-column"> |
| <li class="toc-h2 nav-item toc-entry"><a class="reference internal nav-link" href="#the-three-scalar-shaped-hooks">The three scalar-shaped hooks</a></li> |
| <li class="toc-h2 nav-item toc-entry"><a class="reference internal nav-link" href="#table-functions">Table functions</a></li> |
| <li class="toc-h2 nav-item toc-entry"><a class="reference internal nav-link" href="#serializing-functions">Serializing functions</a></li> |
| </ul> |
| </nav></div> |
| |
| </div></div> |
| |
| |
| </div> |
| <footer class="bd-footer-content"> |
| |
| </footer> |
| |
| </main> |
| </div> |
| </div> |
| |
| <!-- Scripts loaded after <body> so the DOM is not blocked --> |
| <script defer src="../_static/scripts/bootstrap.js?digest=8878045cc6db502f8baf"></script> |
| <script defer src="../_static/scripts/pydata-sphinx-theme.js?digest=8878045cc6db502f8baf"></script> |
| |
| <!-- Based on pydata_sphinx_theme/footer.html --> |
| <footer class="footer mt-5 mt-md-0"> |
| <div class="container"> |
| |
| <div class="footer-item"> |
| <p>Apache Arrow DataFusion, Arrow DataFusion, Apache, the Apache feather logo, and the Apache Arrow DataFusion project logo</p> |
| <p>are either registered trademarks or trademarks of The Apache Software Foundation in the United States and other countries.</p> |
| </div> |
| </div> |
| </footer> |
| |
| |
| </body> |
| </html> |