# Set a query execution deadline

`max_execution_time` limits elapsed SQL processing time for one request. Its value is a finite nonnegative number of seconds; fractional seconds are accepted. A zero database value adds no database deadline, while a nonzero server ceiling still applies.

```sql
SET max_execution_time = 2.5;
```

Send the setting as an administration request, then issue the workload in a later request. Settings are sampled at request start, so changing the value inside a batch does not retroactively change that batch's deadline.

## Check the effective value

```sql
SELECT name, value
FROM system.settings
WHERE name = 'max_execution_time'
FORMAT csv;
```

`SET` persists for the selected database and can affect other clients. It requires autocommit and no active transactions in that database. A saved value cannot relax a stricter XML ceiling.

## Interpret a timeout

The deadline is checked cooperatively. A blocking operation can complete before a later check reports the time-limit error. Socket receive timeouts and an HTTP client's timeout govern different stages. A client timeout alone does not prove whether a write completed; reconcile its result before retrying.

See [max_execution_time](https://coordinatordb.com/docs/reference/settings/session-settings/max-execution), [HTTP requests](https://coordinatordb.com/docs/concepts/features/interfaces/http) and [query history](https://coordinatordb.com/docs/reference/system-tables/query-log).