fix(db): let the maintenance job run behind a pooler that refuses startup options

docs/self-hosting/scaling.md

@@ -195,6 +195,9 @@ in `ignore_startup_parameters`. Either list it there, or set
 `DATABASE_SESSION_OPTIONS_DISABLED=1` so the app sends no session
 settings; set the timeout and `work_mem` on the database role instead
 (`ALTER ROLE healthlog SET work_mem = '16MB'`) if you still want them.
+The measurement maintenance job (Admin, System status) then applies its own
+settings with `SET` after connecting. Its concurrent index rebuild needs a
+session, so run it through a session-mode pool or a direct connection.
 
 ### Overriding the per-container pool ceiling
 

src/lib/jobs/__tests__/measurement-maintenance-session.test.ts

@@ -0,0 +1,30 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("@/lib/db", () => ({
+  prisma: {},
+  sessionOptionsDisabled: () =>
+    process.env.DATABASE_SESSION_OPTIONS_DISABLED === "1",
+}));
+
+import {
+  MAINTENANCE_SESSION_OPTIONS,
+  maintenanceSessionStatements,
+} from "@/lib/jobs/measurement-maintenance";
+
+describe("maintenance session settings behind a pooler", () => {
+  afterEach(() => {
+    delete process.env.DATABASE_SESSION_OPTIONS_DISABLED;
+  });
+
+  it("restates every startup option as one SET statement", () => {
+    const statements = maintenanceSessionStatements();
+    const optionCount = MAINTENANCE_SESSION_OPTIONS.match(/-c /g)?.length;
+    expect(statements).toHaveLength(optionCount ?? 0);
+    expect(statements).toEqual([
+      "SET statement_timeout = '0'",
+      "SET idle_in_transaction_session_timeout = '0'",
+      "SET maintenance_work_mem = '128MB'",
+      "SET lock_timeout = '300000'",
+    ]);
+  });
+});

src/lib/jobs/measurement-maintenance.ts

@@ -35,6 +35,7 @@
  */
 import { Client } from "pg";
 import type { Job } from "pg-boss";
+import { sessionOptionsDisabled } from "@/lib/db";
 
 import { withJobLock } from "@/lib/jobs/job-lock";
 import { jobDone, jobFailed, type JobOutcome } from "@/lib/jobs/job-outcome";
@@ -68,6 +69,21 @@ export interface MeasurementMaintenancePayload {
 export const MAINTENANCE_SESSION_OPTIONS =
   "-c statement_timeout=0 -c idle_in_transaction_session_timeout=0 -c maintenance_work_mem=128MB -c lock_timeout=300000";
 
+/**
+ * The same settings as `SET` statements, for a host behind a connection
+ * pooler that refuses the `options` startup parameter
+ * (`DATABASE_SESSION_OPTIONS_DISABLED`). Built from the constant above, whose
+ * every value is a literal, so nothing user-supplied reaches the SQL.
+ */
+export function maintenanceSessionStatements(): string[] {
+  return MAINTENANCE_SESSION_OPTIONS.split(/\s*-c\s+/)
+    .filter(Boolean)
+    .map((pair) => {
+      const [name, value] = pair.trim().split("=");
+      return `SET ${name} = '${value}'`;
+    });
+}
+
 /** The only shape an index name may have before it is spliced into SQL. */
 const INDEX_NAME = /^[a-z0-9_]{1,63}$/;
 
@@ -310,14 +326,20 @@ export async function handleMeasurementMaintenance(
     const guarded = await withJobLock(
       MEASUREMENT_MAINTENANCE_QUEUE,
       async () => {
+        const viaStatements = sessionOptionsDisabled();
         const client = new Client({
           connectionString: process.env.DATABASE_URL,
-          options: MAINTENANCE_SESSION_OPTIONS,
+          options: viaStatements ? undefined : MAINTENANCE_SESSION_OPTIONS,
           keepAlive: true,
         });
         client.on("error", () => {});
         await client.connect();
         try {
+          if (viaStatements) {
+            for (const statement of maintenanceSessionStatements()) {
+              await client.query(statement);
+            }
+          }
           return await runMeasurementMaintenance(client, payload);
         } finally {
           await client