fix(compute_ctl): Use coalesce without schema as it's not a catalog func

test_runner/regress/test_compute_monitor.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import time
 from typing import TYPE_CHECKING
 
 from fixtures.metrics import parse_metrics
@@ -9,13 +10,13 @@ if TYPE_CHECKING:
     from fixtures.neon_fixtures import NeonEnv
 
 
-def test_compute_monitor(neon_simple_env: NeonEnv):
+def test_compute_monitor_downtime_calculation(neon_simple_env: NeonEnv):
     """
     Test that compute_ctl can detect Postgres going down (unresponsive) and
     reconnect when it comes back online. Also check that the downtime metrics
     are properly emitted.
     """
-    TEST_DB = "test_compute_monitor"
+    TEST_DB = "test_compute_monitor_downtime_calculation"
 
     env = neon_simple_env
     endpoint = env.endpoints.create_start("main")
@@ -68,3 +69,56 @@ def test_compute_monitor(neon_simple_env: NeonEnv):
 
     # Just a sanity check that we log the downtime info
     endpoint.log_contains("downtime_info")
+
+
+def test_compute_monitor_activity(neon_simple_env: NeonEnv):
+    """
+    Test compute monitor correctly detects user activity inside Postgres
+    and updates last_active timestamp in the /status response.
+    """
+    TEST_DB = "test_compute_monitor_activity_db"
+
+    env = neon_simple_env
+    endpoint = env.endpoints.create_start("main")
+
+    with endpoint.cursor() as cursor:
+        # Create a new database because `postgres` DB is excluded
+        # from activity monitoring.
+        cursor.execute(f"CREATE DATABASE {TEST_DB}")
+
+    client = endpoint.http_client()
+
+    prev_last_active = None
+
+    def check_last_active():
+        nonlocal prev_last_active
+
+        with endpoint.cursor(dbname=TEST_DB) as cursor:
+            # Execute some dummy query to generate 'activity'.
+            cursor.execute("SELECT * FROM generate_series(1, 10000)")
+
+        status = client.status()
+        assert status["last_active"] is not None
+        prev_last_active = status["last_active"]
+
+    wait_until(check_last_active)
+
+    assert prev_last_active is not None
+
+    # Sleep for everything to settle down. It's not strictly necessary,
+    # but should still remove any potential noise and/or prevent test from passing
+    # even if compute monitor is not working.
+    time.sleep(3)
+
+    with endpoint.cursor(dbname=TEST_DB) as cursor:
+        cursor.execute("SELECT * FROM generate_series(1, 10000)")
+
+    def check_last_active_updated():
+        nonlocal prev_last_active
+
+        status = client.status()
+        assert status["last_active"] is not None
+        assert status["last_active"] != prev_last_active
+        assert status["last_active"] > prev_last_active
+
+    wait_until(check_last_active_updated)