Refactor PostgreSQL compatibility smoke test runner

Refactored `_fetchrow_required` and introduced multiple helper functions (e.g., `_run_required_fetch`, `_run_optional`) to streamline query execution and improve readability. Organized the script into distinct sections for better maintainability: connectivity, collector, target endpoints, overview, and optional paths. This enhances clarity and ensures consistency in the smoke testing process.

backend/scripts/pg_compat_smoke.py

@@ -31,6 +31,33 @@ async def _fetchrow_required(conn: asyncpg.Connection, query: str, label: str) -
     return dict(row)
 
 
+async def _run_required_fetchrow(conn: asyncpg.Connection, label: str, query: str) -> None:
+    await _fetchrow_required(conn, query, label)
+    print(f"[compat] PASS required: {label}")
+
+
+async def _run_required_fetch(conn: asyncpg.Connection, label: str, query: str) -> None:
+    await conn.fetch(query)
+    print(f"[compat] PASS required: {label}")
+
+
+async def _run_required_fetchval(conn: asyncpg.Connection, label: str, query: str) -> None:
+    await conn.fetchval(query)
+    print(f"[compat] PASS required: {label}")
+
+
+async def _run_optional(conn: asyncpg.Connection, label: str, query: str) -> None:
+    try:
+        await conn.fetch(query)
+        print(f"[compat] PASS optional: {label}")
+    except Exception as exc:
+        print(f"[compat] SKIP optional: {label} ({exc})")
+
+
+def _section(title: str) -> None:
+    print(f"[compat] --- {title} ---")
+
+
 def _dsn_candidates() -> list[str]:
     # Preferred: explicit candidate list for CI portability (Gitea/GitHub runners).
     raw_candidates = os.getenv("PG_DSN_CANDIDATES", "").strip()
@@ -65,9 +92,14 @@ async def run() -> None:
         current_db = await conn.fetchval("SELECT current_database()")
         print(f"[compat] Connected: version={version} db={current_db} dsn={used_dsn}")
 
-        # Core collector queries
-        await _fetchrow_required(
+        _section("connectivity")
+        await _run_required_fetchval(conn, "target_connection.select_1", "SELECT 1")
+
+        _section("collector")
+        # Core collector queries used in app/services/collector.py
+        await _run_required_fetchrow(
             conn,
+            "collector.pg_stat_database",
             """
             SELECT
               numbackends,
@@ -85,11 +117,11 @@ async def run() -> None:
             FROM pg_stat_database
             WHERE datname = current_database()
             """,
-            "pg_stat_database",
         )
 
-        await _fetchrow_required(
+        await _run_required_fetchrow(
             conn,
+            "collector.pg_stat_activity",
             """
             SELECT
               count(*) FILTER (WHERE state = 'active') AS active_connections,
@@ -97,57 +129,149 @@ async def run() -> None:
             FROM pg_stat_activity
             WHERE datname = current_database()
             """,
-            "pg_stat_activity",
         )
 
-        await conn.fetchval("SELECT count(*) FROM pg_locks")
+        await _run_required_fetchval(conn, "collector.pg_locks_count", "SELECT count(*) FROM pg_locks")
 
         # Checkpoint stats fallback (PG14/15 vs newer changes)
         has_checkpointer = await conn.fetchval("SELECT to_regclass('pg_catalog.pg_stat_checkpointer') IS NOT NULL")
         if has_checkpointer:
-            await _fetchrow_required(
+            await _run_required_fetchrow(
                 conn,
-                "SELECT num_timed AS checkpoints_timed, num_requested AS checkpoints_req FROM pg_stat_checkpointer",
-                "pg_stat_checkpointer",
+                "collector.checkpointer_view",
+                """
+                SELECT
+                  num_timed AS checkpoints_timed,
+                  num_requested AS checkpoints_req,
+                  0::bigint AS buffers_checkpoint,
+                  0::bigint AS buffers_clean,
+                  0::bigint AS maxwritten_clean
+                FROM pg_stat_checkpointer
+                """,
             )
             print("[compat] Using pg_stat_checkpointer")
         else:
-            await _fetchrow_required(
+            await _run_required_fetchrow(
                 conn,
-                "SELECT checkpoints_timed, checkpoints_req FROM pg_stat_bgwriter",
-                "pg_stat_bgwriter",
+                "collector.bgwriter_view",
+                "SELECT checkpoints_timed, checkpoints_req, buffers_checkpoint, buffers_clean, maxwritten_clean FROM pg_stat_bgwriter",
             )
             print("[compat] Using pg_stat_bgwriter")
 
-        # Overview queries
-        await conn.fetchval("SELECT pg_is_in_recovery()")
-        await conn.fetchval("SELECT pg_postmaster_start_time()")
-        await conn.fetchval("SELECT inet_server_port()")
-        await conn.fetchval("SELECT pg_database_size(current_database())")
-        await conn.fetch("SELECT datname, pg_database_size(datname) AS size_bytes FROM pg_database ORDER BY size_bytes DESC")
-        await conn.fetch(
+        _section("target endpoints")
+        # Target endpoint queries used in app/api/routes/targets.py
+        await _run_required_fetch(
+            conn,
+            "target_endpoint.locks_table",
+            """
+            SELECT locktype, mode, granted, relation::regclass::text AS relation, pid
+            FROM pg_locks
+            ORDER BY granted ASC, mode
+            LIMIT 500
+            """,
+        )
+        await _run_required_fetch(
+            conn,
+            "target_endpoint.activity_table",
+            """
+            SELECT pid, usename, application_name, client_addr::text, state, wait_event_type, wait_event, now() - query_start AS running_for, left(query, 300) AS query
+            FROM pg_stat_activity
+            WHERE datname = current_database()
+            ORDER BY query_start NULLS LAST
+            LIMIT 200
+            """,
+        )
+
+        _section("overview")
+        # Overview queries used in app/services/overview_collector.py
+        await _run_required_fetchval(conn, "overview.show_server_version", "SHOW server_version")
+        await _run_required_fetchval(conn, "overview.pg_is_in_recovery", "SELECT pg_is_in_recovery()")
+        await _run_required_fetchval(conn, "overview.pg_postmaster_start_time", "SELECT pg_postmaster_start_time()")
+        await _run_required_fetchval(conn, "overview.current_database", "SELECT current_database()")
+        await _run_required_fetchval(conn, "overview.inet_server_port", "SELECT inet_server_port()")
+        await _run_required_fetchval(conn, "overview.pg_database_size_current", "SELECT pg_database_size(current_database())")
+        await _run_required_fetch(
+            conn,
+            "overview.pg_database_size_all",
+            "SELECT datname, pg_database_size(datname) AS size_bytes FROM pg_database ORDER BY size_bytes DESC",
+        )
+        await _run_required_fetch(
+            conn,
+            "overview.largest_tables",
             """
             SELECT schemaname, relname, pg_total_relation_size(schemaname || '.' || relname) AS size_bytes
             FROM pg_stat_user_tables
             ORDER BY size_bytes DESC
             LIMIT 5
-            """
+            """,
         )
-        await conn.fetchval("SELECT COALESCE(sum(size), 0) FROM pg_ls_waldir()")
-
-        # Optional extension check should not fail if unavailable.
-        try:
-            await conn.fetch(
-                """
-                SELECT queryid::text, calls, total_exec_time, mean_exec_time, rows, left(query, 2000) AS query_text
-                FROM pg_stat_statements
-                ORDER BY total_exec_time DESC
-                LIMIT 5
-                """
+        await _run_required_fetchval(conn, "overview.pg_ls_waldir", "SELECT COALESCE(sum(size), 0) FROM pg_ls_waldir()")
+        await _run_required_fetchrow(
+            conn,
+            "overview.performance_pg_stat_database",
+            """
+            SELECT xact_commit, xact_rollback, deadlocks, temp_files, temp_bytes, blk_read_time, blk_write_time
+            FROM pg_stat_database
+            WHERE datname = current_database()
+            """,
+        )
+        await _run_required_fetchval(
+            conn,
+            "overview.autovacuum_activity",
+            """
+            SELECT count(*)
+            FROM pg_stat_activity
+            WHERE query ILIKE 'autovacuum:%'
+            """,
+        )
+        await _run_required_fetchval(
+            conn,
+            "overview.checkpointer_view_exists",
+            "SELECT to_regclass('pg_catalog.pg_stat_checkpointer') IS NOT NULL",
+        )
+        if has_checkpointer:
+            await _run_required_fetchrow(
+                conn,
+                "overview.pg_stat_checkpointer",
+                "SELECT num_timed AS checkpoints_timed, num_requested AS checkpoints_req FROM pg_stat_checkpointer",
             )
-            print("[compat] pg_stat_statements query succeeded")
-        except Exception as exc:
-            print(f"[compat] pg_stat_statements unavailable/disabled (expected in some setups): {exc}")
+        else:
+            await _run_required_fetchrow(
+                conn,
+                "overview.pg_stat_bgwriter",
+                "SELECT checkpoints_timed, checkpoints_req FROM pg_stat_bgwriter",
+            )
+
+        _section("optional paths")
+        # Optional paths that may depend on role/extension config.
+        await _run_optional(conn, "overview.replication_slots", "SELECT count(*) FROM pg_replication_slots")
+        await _run_optional(
+            conn,
+            "overview.pg_stat_replication",
+            """
+            SELECT application_name, client_addr::text, state, sync_state,
+                   EXTRACT(EPOCH FROM write_lag) AS write_lag_seconds,
+                   EXTRACT(EPOCH FROM flush_lag) AS flush_lag_seconds,
+                   EXTRACT(EPOCH FROM replay_lag) AS replay_lag_seconds,
+                   pg_wal_lsn_diff(pg_current_wal_lsn(), replay_lsn) AS replay_lag_bytes
+            FROM pg_stat_replication
+            """,
+        )
+        await _run_optional(
+            conn,
+            "overview.standby_replay_lag",
+            "SELECT EXTRACT(EPOCH FROM (now() - pg_last_xact_replay_timestamp()))",
+        )
+        await _run_optional(
+            conn,
+            "collector.pg_stat_statements",
+            """
+            SELECT queryid::text, calls, total_exec_time, mean_exec_time, rows, left(query, 2000) AS query_text
+            FROM pg_stat_statements
+            ORDER BY total_exec_time DESC
+            LIMIT 20
+            """,
+        )
 
         print("[compat] Smoke checks passed")
     finally: