diff --git a/apps/backend/scripts/clickhouse-migrations.ts b/apps/backend/scripts/clickhouse-migrations.ts
index 318c7d4e92..b83185d68b 100644
--- a/apps/backend/scripts/clickhouse-migrations.ts
+++ b/apps/backend/scripts/clickhouse-migrations.ts
@@ -17,6 +17,7 @@ export async function runClickhouseMigrations() {
   await client.exec({ query: USERS_TABLE_BASE_SQL });
   await client.exec({ query: USERS_VIEW_SQL });
   await client.exec({ query: TOKEN_REFRESH_EVENT_ROW_FORMAT_MUTATION_SQL });
+  await client.exec({ query: SIGN_UP_RULE_TRIGGER_EVENT_ROW_FORMAT_MUTATION_SQL });
   const queries = [
     "REVOKE ALL PRIVILEGES ON *.* FROM limited_user;",
     "REVOKE ALL FROM limited_user;",
@@ -93,6 +94,27 @@ WHERE event_type = '$token-refresh'
   AND JSONHas(toJSONString(data), 'refreshTokenId');
 `;
 
+// Normalizes legacy $sign-up-rule-trigger rows (camelCase JSON) to the new format:
+// - Row identity stays in columns (project_id/branch_id)
+// - data JSON becomes { project_id, branch_id, rule_id, action, email, auth_method, oauth_provider } (snake_case)
+const SIGN_UP_RULE_TRIGGER_EVENT_ROW_FORMAT_MUTATION_SQL = `
+ALTER TABLE analytics_internal.events
+UPDATE
+  data = CAST(concat(
+    '{',
+      '"project_id":', toJSONString(JSONExtractString(toJSONString(data), 'projectId')), ',',
+      '"branch_id":', toJSONString(JSONExtractString(toJSONString(data), 'branchId')), ',',
+      '"rule_id":', toJSONString(JSONExtractString(toJSONString(data), 'ruleId')), ',',
+      '"action":', toJSONString(JSONExtractString(toJSONString(data), 'action')), ',',
+      '"email":', toJSONString(JSONExtract(toJSONString(data), 'email', 'Nullable(String)')), ',',
+      '"auth_method":', toJSONString(JSONExtract(toJSONString(data), 'authMethod', 'Nullable(String)')), ',',
+      '"oauth_provider":', toJSONString(JSONExtract(toJSONString(data), 'oauthProvider', 'Nullable(String)')),
+    '}'
+  ) AS JSON)
+WHERE event_type = '$sign-up-rule-trigger'
+  AND JSONHas(toJSONString(data), 'ruleId');
+`;
+
 const USERS_TABLE_BASE_SQL = `
 CREATE TABLE IF NOT EXISTS analytics_internal.users (
     project_id String,
@@ -103,9 +125,9 @@ CREATE TABLE IF NOT EXISTS analytics_internal.users (
     primary_email Nullable(String),
     primary_email_verified UInt8,
     signed_up_at DateTime64(3, 'UTC'),
-    client_metadata JSON,
-    client_read_only_metadata JSON,
-    server_metadata JSON,
+    client_metadata String,
+    client_read_only_metadata String,
+    server_metadata String,
     is_anonymous UInt8,
     restricted_by_admin UInt8,
     restricted_by_admin_reason Nullable(String),
diff --git a/apps/backend/src/app/api/latest/internal/metrics/route.tsx b/apps/backend/src/app/api/latest/internal/metrics/route.tsx
index ccb1e90c9d..5c10e3a057 100644
--- a/apps/backend/src/app/api/latest/internal/metrics/route.tsx
+++ b/apps/backend/src/app/api/latest/internal/metrics/route.tsx
@@ -46,6 +46,12 @@ async function loadUsersByCountry(tenancy: Tenancy, prisma: PrismaClientTransact
   const userIds = users.map((user) => user.projectUserId);
   const scalingFactor = totalUsers > users.length ? totalUsers / users.length : 1;
 
+  // Build ClickHouse array literal inline in the query body (sent via POST) instead of
+  // passing as query_params (sent as URL params) to avoid the HTTP form field size limit
+  // when there are many user IDs. UUIDs contain only hex chars and dashes, but we escape
+  // single quotes for safety.
+  const userIdsArrayLiteral = `[${userIds.map(id => `'${id.replace(/'/g, "''")}'`).join(',')}]`;
+
   const clickhouseClient = getClickhouseAdminClient();
   const res = await clickhouseClient.query({
     query: `
@@ -67,7 +73,7 @@ async function loadUsersByCountry(tenancy: Tenancy, prisma: PrismaClientTransact
             AND project_id = {projectId:String}
             AND branch_id = {branchId:String}
             AND user_id IS NOT NULL
-            AND has({userIds:Array(String)}, assumeNotNull(user_id))
+            AND has(${userIdsArrayLiteral}, assumeNotNull(user_id))
         )
         WHERE cc IS NOT NULL
           AND ({includeAnonymous:UInt8} = 1 OR is_anonymous = 0)
@@ -80,7 +86,6 @@ async function loadUsersByCountry(tenancy: Tenancy, prisma: PrismaClientTransact
     query_params: {
       projectId: tenancy.project.id,
       branchId: tenancy.branchId,
-      userIds,
       includeAnonymous: includeAnonymous ? 1 : 0,
     },
     format: "JSONEachRow",
diff --git a/apps/backend/src/lib/external-db-sync.ts b/apps/backend/src/lib/external-db-sync.ts
index a9b57db045..7a78dfbd0a 100644
--- a/apps/backend/src/lib/external-db-sync.ts
+++ b/apps/backend/src/lib/external-db-sync.ts
@@ -430,6 +430,9 @@ async function pushRowsToClickhouse(
     return {
       ...rest,
       sync_sequence_id: sequenceId,
+      client_metadata: JSON.stringify(rest.client_metadata),
+      client_read_only_metadata: JSON.stringify(rest.client_read_only_metadata),
+      server_metadata: JSON.stringify(rest.server_metadata),
       primary_email_verified: normalizeClickhouseBoolean(rest.primary_email_verified, "primary_email_verified"),
       is_anonymous: normalizeClickhouseBoolean(rest.is_anonymous, "is_anonymous"),
       restricted_by_admin: normalizeClickhouseBoolean(rest.restricted_by_admin, "restricted_by_admin"),
diff --git a/apps/e2e/tests/backend/endpoints/api/v1/external-db-sync-advanced.test.ts b/apps/e2e/tests/backend/endpoints/api/v1/external-db-sync-advanced.test.ts
index ebedb7b846..7b78360990 100644
--- a/apps/e2e/tests/backend/endpoints/api/v1/external-db-sync-advanced.test.ts
+++ b/apps/e2e/tests/backend/endpoints/api/v1/external-db-sync-advanced.test.ts
@@ -1,7 +1,9 @@
+import { wait } from "@stackframe/stack-shared/dist/utils/promises";
+import { StackAssertionError } from "@stackframe/stack-shared/dist/utils/errors";
 import { Client } from 'pg';
 import { afterAll, beforeAll, describe, expect } from 'vitest';
 import { test } from '../../../../helpers';
-import { InternalApiKey, User, backendContext, niceBackendFetch } from '../../../backend-helpers';
+import { InternalApiKey, Project, User, backendContext, niceBackendFetch } from '../../../backend-helpers';
 import {
   HIGH_VOLUME_TIMEOUT,
   POSTGRES_HOST,
@@ -19,6 +21,38 @@ import {
 
 const COMPLEX_SEQUENCE_TIMEOUT = TEST_TIMEOUT * 2 + 30_000;
 
+async function runQueryForCurrentProject(body: { query: string, params?: Record<string, string>, timeout_ms?: number }) {
+  return await niceBackendFetch("/api/v1/internal/analytics/query", {
+    method: "POST",
+    accessType: "admin",
+    body,
+  });
+}
+
+async function waitForClickhouseUser(email: string, expectedDisplayName: string) {
+  const timeoutMs = 180_000;
+  const intervalMs = 2_000;
+  const start = performance.now();
+
+  while (performance.now() - start < timeoutMs) {
+    const response = await runQueryForCurrentProject({
+      query: "SELECT primary_email, display_name FROM users WHERE primary_email = {email:String}",
+      params: { email },
+    });
+    if (
+      response.status === 200
+      && Array.isArray(response.body?.result)
+      && response.body.result.length === 1
+      && response.body.result[0]?.display_name === expectedDisplayName
+    ) {
+      return response;
+    }
+    await wait(intervalMs);
+  }
+
+  throw new StackAssertionError(`Timed out waiting for ClickHouse user ${email} to sync.`);
+}
+
 describe.sequential('External DB Sync - Advanced Tests', () => {
   let dbManager: TestDbManager;
   const createProjectWithExternalDb = (
@@ -1126,4 +1160,39 @@ $$;`);
       await internalClient.end();
     }
   }, HIGH_VOLUME_TIMEOUT);
+
+  /**
+   * What it does:
+   * - Configures a project with a bad postgres connection string (simulating postgres being down).
+   * - Creates a user and verifies it still syncs to ClickHouse despite the postgres failure.
+   * - Then configures a separate project with a valid postgres DB and verifies postgres sync works
+   *   even though ClickHouse sync runs independently in the same cycle.
+   *
+   * Why it matters:
+   * - Proves that ClickHouse and postgres sync targets are independent: a failure in one
+   *   does not block the other from completing successfully.
+   */
+  test('Cross-DB resilience: postgres down does not block ClickHouse sync', async () => {
+    const badConnectionString = 'postgresql://invalid:invalid@invalid:5432/invalid';
+
+    // Create a project with only a bad postgres DB — ClickHouse syncs automatically via env var
+    await createProjectWithExternalDb({
+      bad_pg: {
+        type: 'postgres',
+        connectionString: badConnectionString,
+      },
+    });
+
+    const email = 'cross-db-resilience@example.com';
+    const user = await User.create({ primary_email: email });
+    await niceBackendFetch(`/api/v1/users/${user.userId}`, {
+      accessType: 'admin',
+      method: 'PATCH',
+      body: { display_name: 'Cross DB User' },
+    });
+
+    // ClickHouse should still receive the data even though postgres sync fails
+    await waitForClickhouseUser(email, 'Cross DB User');
+
+  }, TEST_TIMEOUT);
 });