Simon Willison · · 1 min read

SQLite Query Explainer

Mirrored from Simon Willison for archival readability. Support the source by reading on the original site.

18th July 2026

Tool SQLite Query Explainer — Run SQL queries against a SQLite database in your browser and see exactly how SQLite executes them: the tool runs your query, then annotates every line of both `EXPLAIN QUERY PLAN` and the low-level `EXPLAIN` bytecode output with plain-English descriptions of what the query planner and virtual machine are doing.

Julia Evan's, in Learning a few things about running SQLite:

Maybe one day I’ll learn to read a query plan.

Big same.... which inspired me to have Fable build this interactive explain tool, which runs SQLite in Python in Pyodide in Web Assembly in the browser and adds a layer of explanation to the results of both EXPLAIN and EXPLAIN QUERY PLAN.

Approach with caution, since I don't know enough about SQLite query plans to verify the results myself, but it seems cromulent enough to me.

Posted 18th July 2026 at 5:19 pm

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