> ## Documentation Index
> Fetch the complete documentation index at: https://planetscale.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Extensions: pg_hint_plan
> The pg_hint_plan extension allows you to influence the query planner's decisions by providing hints. It can be used to optimize query performance by guiding the planner towards more efficient execution plans.
export const PlatformAvailability = ({current, vitess, postgres}) => {
const docsHref = path => {
if (!path) return path;
const normalized = path.startsWith('/') ? path : `/${path}`;
return normalized;
};
const labels = {
vitess: 'Vitess',
postgres: 'Postgres'
};
if (current === 'both') {
return
Vitess and Postgres
;
}
const hasVitess = current === 'vitess' || Boolean(vitess);
const hasPostgres = current === 'postgres' || Boolean(postgres);
const only = !(hasVitess && hasPostgres);
const engines = [];
if (current === 'vitess' || current === 'postgres') engines.push(current);
if (hasVitess && current !== 'vitess') engines.push('vitess');
if (hasPostgres && current !== 'postgres') engines.push('postgres');
return
;
};
## Dashboard Configuration
The pg\_hint\_plan extension requires activation via the PlanetScale Dashboard before it can be used. It must be enabled through shared libraries and requires a database restart.
To enable pg\_hint\_plan:
From the PlanetScale organization dashboard, select the desired databaseNavigate to the **Clusters** page from the menu on the leftChoose the branch whose extensions you'd like to configure in the "**Branch**" dropdownSelect the **Extensions** tabEnable pg\_hint\_plan and configure its parametersClick **Queue extension changes** to apply the configurationOnce you're ready to apply the changes, click "**Apply changes**"
## Parameters
### pg\_hint\_plan.enable\_hint
* **Type**: Boolean
* **Default**: `true`
* **Description**: Enable/disable hint functionality.
### pg\_hint\_plan.enable\_hint\_table
* **Type**: Boolean
* **Default**: `false`
* **Description**: Enable hint table functionality.
### pg\_hint\_plan.parse\_messages
* **Type**: Select
* **Options**: error, warning, notice, info, log, debug
* **Default**: `info`
* **Description**: Control parsing message output.
### pg\_hint\_plan.debug\_print
* **Type**: Select
* **Options**: off, on, detailed, verbose
* **Default**: `off`
* **Description**: Enable debug output.
### pg\_hint\_plan.message\_level
* **Type**: Select
* **Options**: error, warning, notice, info, log, debug
* **Default**: `info`
* **Description**: Set message verbosity level.
## Usage
Unlike most PostgreSQL extensions, `pg_hint_plan` does not require `CREATE EXTENSION` to function. Once enabled
through the dashboard, it's automatically loaded and available for use. You only need to run `CREATE EXTENSION` if you
plan to use the hint table functionality (when `pg_hint_plan.enable_hint_table` is enabled).
After enabling the extension through the dashboard, you can optionally install it in your database for hint table functionality:
```sql theme={null}
-- Only required if using hint tables
CREATE EXTENSION IF NOT EXISTS pg_hint_plan;
```
Then you can use hints in your queries:
```sql theme={null}
/*+
SeqScan(t1)
IndexScan(t2 t2_pkey)
*/
SELECT * FROM table1 t1 JOIN table2 t2 ON t1.id = t2.id;
```
## External Documentation
For more detailed information about pg\_hint\_plan usage and hint syntax, see the [official pg\_hint\_plan documentation](https://github.com/ossc-db/pg_hint_plan).