# Slow Query Log

This page covers the slow query log built into `query()`: what it times, what it prints, and what it leaves out.

## Behavior

Every SQL statement runs through `query()` (`src/MySQLPool.ts:362-392`). When a run takes more than 20ms, it prints one line through `console.log`:

```text
[Slow Query: 37ms] [SELECT * FROM `users` WHERE `status` = ?]
```

| Item | Detail |
|---|---|
| Threshold | 20ms (logged when above 20) |
| Timed span | From just before `pool.getConnection()` until the result returns, including time spent waiting for a free connection |
| Output | Duration and the SQL with `?` placeholders, **without** bound values |
| Destination | `console.log` (stdout) |

## Reading the Log

Because the timer includes connection checkout, fast SQL still gets logged when the pool is saturated. When slow entries pile up, check:

| Symptom | Likely cause |
|---|---|
| The same SQL is sometimes fast, and slow entries cluster under load | Pool queueing; consider raising `connectionLimit` (see [Configuration](/configuration)) |
| One statement always crosses the threshold | The SQL itself is slow; inspect indexes with `EXPLAIN` |

## Related Pages

- [Raw SQL](/raw-sql)
- [Architecture](/architecture)