Allow configuring the connection pool size

Closes #3165

api/src/database/index.ts

@@ -14,8 +14,11 @@ const connectionConfig: Record<string, any> = getConfigFromEnv('DB_', [
 	'DB_CLIENT',
 	'DB_SEARCH_PATH',
 	'DB_CONNECTION_STRING',
+	'DB_POOL',
 ]);
 
+const poolConfig = getConfigFromEnv('DB_POOL');
+
 const knexConfig: Config = {
 	client: env.DB_CLIENT,
 	searchPath: env.DB_SEARCH_PATH,
@@ -26,6 +29,7 @@ const knexConfig: Config = {
 		deprecate: (msg) => logger.info(msg),
 		debug: (msg) => logger.debug(msg),
 	},
+	pool: poolConfig,
 };
 
 if (env.DB_CLIENT === 'sqlite3') {

docs/reference/environment-variables.md

@@ -28,6 +28,7 @@
 | `DB_PASSWORD`          | Database user's password. **Required** when using `pg`, `mysql`, `oracledb`, or `mssql`.                                                           | --            |
 | `DB_FILENAME`          | Where to read/write the SQLite database. **Required** when using `sqlite3`.                                                                        | --            |
 | `DB_CONNECTION_STRING` | When using `pg`, you can submit a connection string instead of individual properties. Using this will ignore any of the other connection settings. | --            |
+| `DB_POOL_*`            | Pooling settings. Passed on to [the `tarn.js`](https://github.com/vincit/tarn.js#usage) library.                                                   | --            |
 
 ::: tip Additional Database Variables
 
@@ -37,6 +38,13 @@ database instance.
 
 :::
 
+::: tip Pooling
+
+All the `DB_POOL_` prefixed options are passed [to `tarn.js`](https://github.com/vincit/tarn.js#usage) through
+[Knex](http://knexjs.org/#Installation-pooling)
+
+:::
+
 ## Security
 
 | Variable                         | Description                                                                                      | Default Value |