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README.md

Trino documentation

The docs module contains the reference documentation for Trino.

Writing and contributing

We welcome any contributions to the documentation. Contributions must follow the same process as code contributions and can be part of your code contributions or separate documentation improvements.

The documentation follows the Google developer documentation style guide for any new documentation:

The Google guidelines include more material than listed here, and are used as a guide that enable easy decision making about proposed doc changes. Changes to existing documentation to follow these guidelines are underway.

As a specific style note, because different readers may perceive the phrases "a SQL" or "an SQL" to be incorrect depending on how they pronounce SQL, aim to avoid use of "a/an SQL" in Trino documentation. Try to reword, re-order, or adjust writing so that it is not necessary. If there is absolutely no way around it, default to using "a SQL."

Other useful resources:

Tools

Documentation source files can be found in Restructured Text (.rst) format in src/main/sphinx and sub-folders.

The engine used to create the documentation in HTML format is the Python-based Sphinx.

The fast doc build option requires only a local installation of Docker Desktop on Mac or Docker Engine on Linux. No other tools are required.

The default formal build of the docs is performed with Apache Maven, which requires an installation of a Java Development Kit.

Fast doc build option

For fast local build times when writing documentation, you can run the Sphinx build directly. The build runs inside a Docker container and thus does not require having anything installed locally other than Docker. You can run the Sphinx build on a fresh clone of the project, with no prerequisite commands. For example:

docs/build

Sphinx attempts to perform an incremental build, but this does not work in all cases, such as after editing the CSS. You can force a full rebuild by removing the target/html directory:

rm -rf docs/target/html

Default build

The default build uses Apache Maven and Java as does the rest of the Trino build. You only need to have built the current Trino version from the root. That is, before building the docs the first time, run the following command:

./mvnw clean install -DskipTests

Subsequently, you can build the doc site using the Maven wrapper script:

./mvnw -pl docs clean install

If you have Maven installed and available on the path, you can use the mvn command directly.

This also performs other checks, and is the authoritative way to build the docs. However, using Maven is also somewhat slower than using Sphinx directly.

Viewing documentation

However you build the docs, the generated HTML files can be found in the folder docs/target/html/.

You can open the file docs/target/html/index.html in a web browser on macOS with

open docs/target/html/index.html

or on Linux with

xdg-open docs/target/html/index.html

Or you can directly call your browser of choice with the same filename. For example, on Ubuntu with Chromium:

chromium-browser docs/target/html/index.html

Alternatively, you can start a web server with that folder as root, such as with the following Python command. You can then open http://localhost:4000 in a web browser.

cd docs/target/html/
python3 -m http.server 4000

In order to see any changes from the source files in the HTML output, simply re-run the build command and refresh the browser.

Versioning

The version displayed in the resulting HTML is read by default from the top level Maven pom.xml file version field.

To deploy a specific documentation set (such as a SNAPSHOT version) as the release version you must override the pom version with the TRINO_VERSION environment variable.

TRINO_VERSION=355 docs/build

If you work on the docs for more than one invocation, you can export the variable and use it with Sphinx.

export TRINO_VERSION=354
docs/build

This is especially useful when deploying doc patches for a release where the Maven pom has already moved to the next SNAPSHOT version.

Style check

The project contains a configured setup for Vale and the Google developer documentation style. Vale is a command-line tool to check for editorial style issues of a document or a set of documents.

Install vale with brew on macOS or follow the instructions on the website.

brew install vale

The docs folder contains the necessary configuration to use vale for any document in the repository:

  • .vale directory with Google style setup
  • .vale/Vocab/Base/accept.txt file for additional approved words and spelling
  • .vale.ini configuration file configured for rst and md files

With this setup you can validate an individual file from the root by specifying the path:

vale src/main/sphinx/overview/sep-ui.rst

You can also use directory paths and all files within.

Treat all output from vale as another help towards better docs. Fixing any issues is not required, but can help with learning more about the Google style guide that we try to follow.

Contribution requirements

To contribute corrections or new explanations to the Trino documentation requires only a willingness to help and submission of your Contributor License Agreement (CLA).

Workflow

The procedure to add a documentation contribution is the same as for a code contribution.

  • In the Trino project's GitHub Issues list, identify documentation issues by filtering on the docs label.

  • If you want to help Trino documentation, but don't know where to start, look in the Issues list for both the docs and good first issue labels.

  • If the doc fix you have in mind does not yet have an issue, add one (which requires a signed CLA). Add the docs label to your new issue.

  • You can discuss proposed doc changes in the #docs channel of the Trino Slack.

  • For a larger contribution, create a GitHub pull request as described in GitHub documentation. In brief, this means:

    • Create a fork of the trinodb/trino repository.

    • Create a working branch in your fork.

    • Make your edits in your working branch and push them to your fork.

    • In a browser, open your fork in GitHub, which offers to submit a pull request for you.

Videos

  1. See Contributing to the Trino documentation for a five-minute video introduction.

  2. You might select a GitHub doc issue to work on that requires you to verify how Trino handles a situation, such as adding documentation for SQL functions.

    In this case, the five-minute video Learning Trino SQL with Docker gives you a starting point for setting up a test system on your laptop.