Simon Willison Unveils an Interactive SQLite Query Explainer

Developer Simon Willison has introduced a new tool, the SQLite Query Explainer — an interactive web app that helps make sense of SQLite query execution plans.

What Sparked the Idea

The catalyst was a note by programmer Julia Evans, “Learning a few things about running SQLite,” in which she admitted she hopes to someday learn how to read a query plan. That remark inspired Willison to build a tool of his own.

How It Works

The implementation was handled by the AI model Fable, which Willison asked to build an interactive explain tool. SQLite itself runs right in the browser: the Python interpreter operates via Pyodide, compiled to WebAssembly. On top of the standard output of the EXPLAIN and EXPLAIN QUERY PLAN commands, the tool adds a layer of plain-language explanations.

The Author's Caveat

Willison himself warns that he doesn't know enough about the inner workings of SQLite query plans to verify the accuracy of the explanations on his own. In his words, the results look plausible enough, but the tool should be used with caution.

The project demonstrates how modern web technologies — Pyodide and WebAssembly — make it possible to run full-fledged databases and analysis tools right in the browser, with no additional software to install.

Source: Simon Willison