perf(db): drive Postgres pool size + application_name from per-role profiles

Replace ad-hoc DB_APP_NAME sizing with a per-role profile map keyed by
SIM_DB_ROLE (web/trigger/realtime), defaulting to web. Trigger machines
open a small pool instead of 15 to avoid PgBouncer connection exhaustion.
Also size realtime's separate socketDb pool down to 10.

Author: TheodoreSpeaks

apps/realtime/src/database/operations.ts

@@ -32,13 +32,14 @@ import { env } from '@/env'
 const logger = createLogger('SocketDatabase')
 
 const connectionString = env.DATABASE_URL
+// Realtime process footprint = this socketDb pool + the shared @sim/db pool.
 const socketDb = drizzle(
   instrumentPoolClient(
     postgres(connectionString, {
       prepare: false,
       idle_timeout: 10,
       connect_timeout: 20,
-      max: 15,
+      max: 10,
       onnotice: () => {},
       connection: { application_name: process.env.DB_APP_NAME ?? 'sim-realtime' },
     }),

apps/realtime/src/env.ts

@@ -13,6 +13,7 @@ const EnvSchema = z.object({
   NEXT_PUBLIC_APP_URL: z.string().url(),
   ALLOWED_ORIGINS: z.string().optional(),
   PORT: z.coerce.number().int().positive().default(3002),
+  SIM_DB_ROLE: z.enum(['web', 'trigger', 'realtime']).optional(),
   DISABLE_AUTH: z
     .string()
     .optional()

apps/sim/lib/core/config/env.ts

@@ -21,6 +21,7 @@ export const env = createEnv({
     DATABASE_URL:                          z.string().url(),                       // Primary database connection string
     DATABASE_REPLICA_URL:                  z.string().url().optional(),            // Read-replica connection string; opt-in reads fall back to the primary when unset
     DB_APP_NAME:                           z.string().optional(),                  // Postgres application_name for query attribution (sim-app/sim-trigger/sim-realtime)
+    SIM_DB_ROLE:                           z.enum(['web', 'trigger', 'realtime']).optional(), // Per-process pool profile selector (read directly by @sim/db)
     BETTER_AUTH_URL:                       z.string().url(),                       // Base URL for Better Auth service
     BETTER_AUTH_SECRET:                    z.string().min(32),                     // Secret key for Better Auth JWT signing
     DISABLE_REGISTRATION:                  z.boolean().optional(),                 // Flag to disable new user registration

packages/db/db.ts

@@ -8,16 +8,33 @@ if (!connectionString) {
   throw new Error('Missing DATABASE_URL environment variable')
 }
 
+/**
+ * Per-role pool profiles. Starting numbers — validate against real per-role
+ * process counts (PgBouncer transaction mode, max_connections=200).
+ */
+export const DB_POOL_PROFILES = {
+  web: { primaryMax: 10, replicaMax: 4, appName: 'sim-app' },
+  // 5, not 3 — one run can need 3+ simultaneous connections (parallel queries +
+  // overlapping logging writes); 3 risks intra-run deadlock.
+  trigger: { primaryMax: 5, replicaMax: 2, appName: 'sim-trigger' },
+  realtime: { primaryMax: 5, replicaMax: 3, appName: 'sim-realtime' },
+} as const
+
+type DbRole = keyof typeof DB_POOL_PROFILES
+
+const role = process.env.SIM_DB_ROLE as DbRole | undefined
+const profile = (role && DB_POOL_PROFILES[role]) || DB_POOL_PROFILES.web
+
 const poolOptions = {
   prepare: false,
   idle_timeout: 20,
   connect_timeout: 30,
   onnotice: () => {},
-  connection: { application_name: process.env.DB_APP_NAME ?? 'sim-app' },
+  connection: { application_name: process.env.DB_APP_NAME ?? profile.appName },
 }
 
 const postgresClient = instrumentPoolClient(
-  postgres(connectionString, { ...poolOptions, max: 15 }),
+  postgres(connectionString, { ...poolOptions, max: profile.primaryMax }),
   'db'
 )
 
@@ -37,7 +54,13 @@ if (replicaUrl && !/^postgres(ql)?:\/\//.test(replicaUrl)) {
 }
 
 export const dbReplica: typeof db = replicaUrl
-  ? drizzle(instrumentPoolClient(postgres(replicaUrl, { ...poolOptions, max: 10 }), 'dbReplica'), {
-      schema,
-    })
+  ? drizzle(
+      instrumentPoolClient(
+        postgres(replicaUrl, { ...poolOptions, max: profile.replicaMax }),
+        'dbReplica'
+      ),
+      {
+        schema,
+      }
+    )
   : db