#Malloy

Malloy is an open source language for describing data relationships and transformations. It is both a semantic modeling language and a querying language that runs queries against a relational database. Malloy supports every database connection registered by the core @malloydata/malloy library — at the time of writing that includes BigQuery, Postgres, MySQL, Snowflake, MotherDuck, DuckDB, Presto, and Trino. The list grows with each release; the live set is whatever shows up in the connection editor in your installed version.

We've built a Visual Studio Code extension to facilitate building Malloy data models, querying and transforming data, and creating simple visualizations and dashboards.

###Click here to try Malloy in your browser!

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##Install the Visual Studio Code Extension locally

To write your own Malloy models, use the VS Code Extension, currently available for Mac, Linux, and Windows machines.

1. ›

   Download Visual Studio Code: Download Visual Studio Code

2. ›

   Add the Malloy (pre-release) extension from the Visual Studio Code Marketplace: Open VS Code and click the Extensions button on the far left (it looks like 4 blocks with one flying away). This will open the Extension Marketplace. Search for "Malloy" and, once found, click "Install"

3. ›

   Download and unzip the Sample Models (models + data).

4. ›

   Open the samples folder in VS Code. In VS Code, go to File > Open Folder... select malloy-samples/duckdb > Open. DuckDB is built into the extension so you're ready to run these.

5. ›

   Start with 1_airports.malloy in the FAA dataset. This is a sub-sample of the NTSB Flights dataset. In the editor pane, above source: airports, click the word "Preview" to run a SELECT *, and click the word "Run" above any query object to run it (see gif below for example).

To get to know the Malloy language, follow the Quickstart guide and/or continue through the numbered models in the FAA directory.

Note: The Malloy VSCode Extension tracks a small amount of anonymous usage data. You can opt out in the extension settings. Learn more.

##Join the Community

• ›Join our Malloy Slack Community! Use this community to ask questions, meet other Malloy users, and share ideas with one another.
• ›Use GitHub issues in this Repo to provide feedback, suggest improvements, report bugs, and start new discussions.

##Resources

Documentation:

• ›Malloy Language - A quick introduction to the language
• ›eCommerce Example Analysis - a walkthrough of the basics on an ecommerce dataset (BigQuery public dataset)
• ›Modeling Walkthrough - introduction to modeling via the Iowa liquor sales public data set (BigQuery public dataset)

YouTube - Watch demos / walkthroughs of Malloy

##Contributing

If you would like to work on the Malloy VS Code extension, take a look at the instructions for developing.

To report security issues please see our security policy.

Malloy is not an officially supported Google product.

##Syntax Example

Here is a simple example of a Malloy query:

query: table('malloy-data.faa.flights') -> {
  where: origin ? 'SFO'
  group_by: carrier
  aggregate:
    flight_count is count()
    average_flight_time is flight_time.avg()
}

In SQL this would be expressed:

SELECT
   carrier,
   COUNT(*) as flight_count,
   AVG(flight_time) as average_flight_time
FROM `malloy-data.faa.flights`
WHERE origin = 'SFO'
GROUP BY carrier
ORDER BY flight_count desc         -- malloy automatically orders by the first aggregate

Learn more about the syntax and language features of Malloy in the Quickstart.