Slow POST /metadata (GetCurrentUser) due to PostgreSQL connection pool cold start

https://sonarly.com/issue/12283?type=bug

The `GetCurrentUser` GraphQL query on `POST /metadata` takes ~2.9s during workspace creation because 6 concurrent `pg.connect` operations each take 1.1-1.4s to establish new TCP connections to PostgreSQL, indicating an exhausted or cold connection pool.

Fix: Added a `PG_POOL_MIN_CONNECTIONS` configuration variable (default: 5) to maintain a minimum number of warm PostgreSQL connections in the pool, preventing the cold-start latency observed in the Sentry trace.

The trace showed 6 concurrent `pg.connect` operations each taking 1.1-1.4 seconds — these were new TCP+SSL connection establishments because the pool had no available connections. By setting a minimum pool size, the `pg.Pool` will proactively maintain at least 5 connections, so burst queries during auth middleware execution (GetCurrentUser resolver) can reuse existing connections instead of waiting for new ones.

**Changes:**

1. **`config-variables.ts`**: Added `PG_POOL_MIN_CONNECTIONS` config variable with default value of 5, following the exact same pattern as `PG_POOL_MAX_CONNECTIONS` (same decorators, metadata group, type).

2. **`global-workspace-datasource.service.ts`**: Added `min` to the `extra` pool options for both primary and replica DataSource configurations, reading from `PG_POOL_MIN_CONNECTIONS`.

3. **`core.datasource.ts`**: Added `min` to the core DataSource's `extra` config, using `process.env.PG_POOL_MIN_CONNECTIONS` (matching the existing pattern of using raw env vars in this static config file).

The `min` option is a standard `pg.Pool` parameter that TypeORM passes through via the `extra` config. This ensures the pool eagerly creates and maintains connections rather than starting from zero.

packages/twenty-server/src/database/typeorm/core/core.datasource.ts

@@ -73,6 +73,7 @@ export const typeORMCoreModuleOptions: TypeOrmModuleOptions = {
       : undefined,
   extra: {
     query_timeout: 15000,
+    min: parseInt(process.env.PG_POOL_MIN_CONNECTIONS ?? '5', 10),
   },
 };
 

packages/twenty-server/src/engine/core-modules/twenty-config/config-variables.ts

@@ -927,6 +927,17 @@ export class ConfigVariables {
   @IsOptional()
   PG_POOL_MAX_CONNECTIONS = 10;
 
+  @ConfigVariablesMetadata({
+    group: ConfigVariablesGroup.SERVER_CONFIG,
+    description:
+      'Minimum number of clients maintained in pg connection pool to avoid cold start latency',
+    isEnvOnly: true,
+    type: ConfigVariableType.NUMBER,
+  })
+  @CastToPositiveNumber()
+  @IsOptional()
+  PG_POOL_MIN_CONNECTIONS = 5;
+
   @ConfigVariablesMetadata({
     group: ConfigVariablesGroup.SERVER_CONFIG,
     description: 'Idle timeout in milliseconds for pg connection pool clients',

packages/twenty-server/src/engine/twenty-orm/global-workspace-datasource/global-workspace-datasource.service.ts

@@ -44,6 +44,7 @@ export class GlobalWorkspaceDataSourceService
           query_timeout: this.twentyConfigService.get(
             'PG_DATABASE_PRIMARY_TIMEOUT_MS',
           ),
+          min: this.twentyConfigService.get('PG_POOL_MIN_CONNECTIONS'),
           idleTimeoutMillis: this.twentyConfigService.get(
             'PG_POOL_IDLE_TIMEOUT_MS',
           ),
@@ -79,6 +80,7 @@ export class GlobalWorkspaceDataSourceService
             query_timeout: this.twentyConfigService.get(
               'PG_DATABASE_REPLICA_TIMEOUT_MS',
             ),
+            min: this.twentyConfigService.get('PG_POOL_MIN_CONNECTIONS'),
             idleTimeoutMillis: this.twentyConfigService.get(
               'PG_POOL_IDLE_TIMEOUT_MS',
             ),