# Explain Plan (Single-Stage)

Use `EXPLAIN PLAN FOR` when you want to understand how Pinot will execute a query before or while tuning it.

## What it tells you

Explain plan output helps you see:

* which operators Pinot will run
* whether an index is being used
* where filters, projections, and aggregations happen
* how a query is shaped in single-stage or multi-stage execution

```sql
EXPLAIN PLAN FOR
SELECT city, COUNT(*)
FROM stores
GROUP BY city;
```

## Single-stage and multi-stage

Single-stage explain plans are best for understanding the operator flow behind straightforward queries.

Multi-stage explain plans are better when you need to inspect joins, subqueries, or the distributed execution shape.

## How to use it

Start with explain plan when a query is:

* slower than expected
* not using the index you expected
* returning a shape that is hard to reason about

Then pair the plan with query options or index guidance if you need a fix.

## What this page covered

This page covered what explain plan shows, when to use it, and how the single-stage and multi-stage engines differ.

## Next step

If you need a deeper execution-shape discussion, read [SQL syntax](https://docs.pinot.apache.org/build-with-pinot/querying-and-sql/sql-syntax) and then revisit query options or quotas if the issue is runtime control rather than syntax.

## Related pages

* [Query options](https://docs.pinot.apache.org/build-with-pinot/querying-and-sql/query-execution-controls/query-options)
* [Querying Pinot](https://docs.pinot.apache.org/build-with-pinot/querying-and-sql/querying-pinot)
* [SQL syntax](https://docs.pinot.apache.org/build-with-pinot/querying-and-sql/sql-syntax)