fix(postgres): explain a dropped table instead of raw driver text

products/warehouse_sources/backend/temporal/data_imports/sources/postgres/source.py

@@ -514,7 +514,16 @@ def get_non_retryable_errors(self) -> dict[str, str | None]:
                 "dashboard for this branch's connection settings, then re-enable the sync."
             ),
             "FATAL: no such database": None,
-            "does not exist": None,
+            # A relation or column the sync reads was dropped or renamed on the source, so the
+            # streaming query fails with SQLSTATE 42P01 ("relation ... does not exist") or 42703
+            # ("column ... does not exist"). The stored schema/query is fixed until the customer
+            # changes it, so every retry replays the same statement. Already non-retryable through
+            # this bucket; the actionable message replaces the raw psycopg text, which echoes the
+            # relation name and a SQL fragment back into `latest_error`.
+            "does not exist": (
+                "A table or column this sync reads no longer exists in your source database. Remove it "
+                "from the source's selected tables, or reset and re-sync this table, then re-enable the sync."
+            ),
             "timestamp too small": None,
             "QueryTimeoutException": None,
             # Activity-layer twin of the `QueryTimeoutException` key above. That key only matches once

products/warehouse_sources/backend/temporal/data_imports/sources/postgres/test_postgres.py

@@ -453,6 +453,22 @@ def test_unrecognized_session_parameter_surfaces_actionable_message(self, source
         assert matches[0] is not None, "unrecognized session parameter must surface an actionable message"
         assert "session setting" in matches[0].lower()
 
+    def test_missing_relation_surfaces_actionable_message(self, source):
+        # A dropped/renamed table or column stays non-retryable, but must surface an actionable
+        # message rather than the raw psycopg text (which echoes the relation name and SQL fragment).
+        # Mirror the finalizer's first-match selection so a reorder that shadows it with an earlier
+        # None-valued key, or a revert of this bucket back to None, is caught. The relation name is
+        # invented, not a real customer value.
+        error_msg = 'relation "public.orders" does not exist LINE 1: DECLARE _cur CURSOR FOR SELECT * FROM "public"."orders"'
+        matches = [
+            friendly
+            for pattern, friendly in source.get_non_retryable_errors().items()
+            if error_message_matches(error_msg, [pattern])
+        ]
+        assert matches, "a dropped relation must be classified non-retryable"
+        assert matches[0] is not None, "a dropped relation must surface an actionable message, not raw driver text"
+        assert "no longer exists" in matches[0].lower()
+
     def test_connect_timeout_surfaces_actionable_message(self, source):
         # A persistently timing-out connect stays non-retryable, but must surface firewall/reachability
         # guidance rather than the bare "connection timeout expired" driver text. Mirror the finalizer's

products/warehouse_sources/backend/temporal/data_imports/sources/supabase/test_supabase_source.py

@@ -231,21 +231,24 @@ def _resolve_friendly_error(source: SupabaseSource, raw_error: str) -> str | Non
 
 
 @pytest.mark.parametrize(
-    "raw_error,expect_message",
+    "raw_error,expect_realtime_message",
     [
-        # Retention dropped the dated realtime.messages partition — actionable message, not the
-        # inherited generic "does not exist" (which resolves to None / the raw driver string).
+        # Retention dropped the dated realtime.messages partition, so its specific realtime message
+        # must win over the inherited generic "does not exist" bucket (first matching key wins).
         ('relation "realtime.messages_2020_01_01" does not exist', True),
-        # A regular missing table must still fall through to the generic (None) mapping, so the
+        # A regular missing table must fall through to the generic missing-relation message, so the
         # realtime key stays specific and doesn't swallow every "does not exist".
         ('relation "public.orders" does not exist', False),
     ],
 )
-def test_expired_realtime_partition_gets_actionable_message(raw_error, expect_message):
+def test_expired_realtime_partition_gets_actionable_message(raw_error, expect_realtime_message):
     friendly = _resolve_friendly_error(SupabaseSource(), raw_error)
 
-    if expect_message:
-        assert friendly is not None
+    # Both cases are non-retryable with an actionable message now; only the realtime partition gets
+    # the realtime-specific copy.
+    assert friendly is not None
+    if expect_realtime_message:
         assert "realtime.messages" in friendly
     else:
-        assert friendly is None
+        assert "realtime.messages" not in friendly
+        assert "no longer exists" in friendly.lower()