# Explain or profile a query plan

Control / log

A variant of [Log and annotate a run](https://meridian.online/operations/log-and-annotate-a-run).

Show the plan a query will run, or run it and report where the time went.

Page: <https://meridian.online/operations/log-and-annotate-a-run/explain-a-query-plan>

## Status

Not built yet.

arcform does not do this yet; it would live in how a Protocol runs. [Its place on the roadmap](https://meridian.online/roadmap#log-and-annotate-a-run)

## What other tools call it

Meridian's classification; an independent blind rating agreed on 95.7% of 324 rows (variant, version 3).

- Apache DataFusion: [`EXPLAIN`](https://datafusion.apache.org/user-guide/sql/explain.html) (read 2026-09-27)
- Apache DataFusion: [`EXPLAIN ANALYZE`](https://datafusion.apache.org/user-guide/sql/explain.html) (read 2026-09-27)
- Apache DataFusion: [`explain`](https://docs.rs/datafusion/latest/datafusion/dataframe/struct.DataFrame.html) (read 2026-09-27)
- DuckDB: [`Profiling`](https://duckdb.org/docs/current/sql/statements/profiling) (read 2026-09-27)
- Polars: [`Expr.meta (group)`](https://docs.pola.rs/api/python/stable/reference/expressions/meta.html) (read 2026-09-27)
- Polars: [`LazyFrame query plan inspection (family)`](https://docs.pola.rs/api/python/stable/reference/lazyframe/descriptive.html) (read 2026-09-27)