feat(core): Add mysql pool size and increase it for CI (no-changelog) (#19347)

packages/@n8n/config/src/configs/database.config.ts

@@ -113,6 +113,10 @@ class MysqlConfig {
 	/** MySQL database user */
 	@Env('DB_MYSQLDB_USER')
 	user: string = 'root';
+
+	/** MySQL connection pool size */
+	@Env('DB_MYSQLDB_POOL_SIZE')
+	poolSize: number = 10;
 }
 
 @Config

packages/@n8n/config/test/config.test.ts

@@ -69,6 +69,7 @@ describe('GlobalConfig', () => {
 				password: '',
 				port: 3306,
 				user: 'root',
+				poolSize: 10,
 			},
 			postgresdb: {
 				database: 'n8n',