fix(restore): run --empty pre-clean per statement and drop non-public schemas

One DO-block ran every DROP in a single transaction and exhausted
max_locks_per_transaction on large schemas (gitlab); emit one DROP per
row and execute via \gexec instead. Also drop user-owned non-public
schemas so a dump that CREATE SCHEMAs (discourse) does not abort on the
existing schema under ON_ERROR_STOP.

Covered by a new DinD e2e test restoring --empty against a fully
populated database with a non-public schema and every object class.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/e2e/test_e2e_postgres_empty_drop_hard.py

@@ -0,0 +1,157 @@
+# tests/e2e/test_e2e_postgres_empty_drop_hard.py
+import unittest
+
+from .helpers import (
+    POSTGRES_IMAGE,
+    POSTGRES_DATA_DIR,
+    backup_run,
+    cleanup_docker,
+    create_minimal_compose_dir,
+    ensure_empty_dir,
+    latest_version_dir,
+    require_docker,
+    run,
+    unique,
+    wait_for_postgres,
+    write_databases_csv,
+)
+
+# The scenario the --empty pre-clean must survive: a non-public user schema
+# plus one object of every class the discovery SELECT enumerates. Restore
+# --empty runs against the still-populated DB (no wipe), so the pre-clean must
+# drop discourse_functions too or the dump's CREATE SCHEMA aborts the replay
+# under ON_ERROR_STOP; the old public-only DROP left it and broke discourse.
+SCENARIO_SQL = (
+    "CREATE SCHEMA discourse_functions;"
+    "CREATE TABLE discourse_functions.helper (id int);"
+    "INSERT INTO discourse_functions.helper VALUES (1);"
+    "CREATE TABLE public.t (id int primary key, v text);"
+    "INSERT INTO public.t VALUES (1, 'ok');"
+    "CREATE VIEW public.t_view AS SELECT * FROM public.t;"
+    "CREATE SEQUENCE public.s;"
+    "CREATE TYPE public.mood AS ENUM ('ok', 'bad');"
+    "CREATE FUNCTION public.f() RETURNS int LANGUAGE sql AS 'SELECT 1';"
+    "CREATE COLLATION public.c (locale = 'C');"
+)
+
+
+class TestE2EPostgresEmptyDropHard(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls) -> None:
+        require_docker()
+        cls.prefix = unique("baudolo-e2e-postgres-empty-drop-hard")
+        cls.backups_dir = f"/tmp/{cls.prefix}/Backups"
+        ensure_empty_dir(cls.backups_dir)
+        cls.compose_dir = create_minimal_compose_dir(f"/tmp/{cls.prefix}")
+        cls.repo_name = cls.prefix
+
+        cls.pg_container = f"{cls.prefix}-pg"
+        cls.pg_volume = f"{cls.prefix}-pg-vol"
+        cls.containers = [cls.pg_container]
+        cls.volumes = [cls.pg_volume]
+
+        run(["docker", "volume", "create", cls.pg_volume])
+        run(
+            [
+                "docker",
+                "run",
+                "-d",
+                "--name",
+                cls.pg_container,
+                "-e",
+                "POSTGRES_PASSWORD=pgpw",
+                "-e",
+                "POSTGRES_DB=appdb",
+                "-e",
+                "POSTGRES_USER=postgres",
+                "-v",
+                f"{cls.pg_volume}:{POSTGRES_DATA_DIR}",
+                POSTGRES_IMAGE,
+            ]
+        )
+        wait_for_postgres(cls.pg_container, user="postgres", timeout_s=90)
+
+        run(
+            [
+                "docker",
+                "exec",
+                cls.pg_container,
+                "sh",
+                "-lc",
+                f'psql -U postgres -d appdb -v ON_ERROR_STOP=1 -c "{SCENARIO_SQL}"',
+            ]
+        )
+
+        cls.databases_csv = f"/tmp/{cls.prefix}/databases.csv"
+        write_databases_csv(
+            cls.databases_csv, [(cls.pg_container, "appdb", "postgres", "pgpw")]
+        )
+        backup_run(
+            backups_dir=cls.backups_dir,
+            repo_name=cls.repo_name,
+            compose_dir=cls.compose_dir,
+            databases_csv=cls.databases_csv,
+            database_containers=[cls.pg_container],
+            images_no_stop_required=[POSTGRES_IMAGE],
+        )
+        cls.hash, cls.version = latest_version_dir(cls.backups_dir, cls.repo_name)
+
+        # No wipe: restore --empty must pre-clean the fully-populated DB
+        # (incl. the non-public schema) before replaying the dump.
+        run(
+            [
+                "baudolo-restore",
+                "postgres",
+                cls.pg_volume,
+                cls.hash,
+                cls.version,
+                "--backups-dir",
+                cls.backups_dir,
+                "--repo-name",
+                cls.repo_name,
+                "--container",
+                cls.pg_container,
+                "--db-name",
+                "appdb",
+                "--db-user",
+                "postgres",
+                "--db-password",
+                "pgpw",
+                "--empty",
+            ]
+        )
+
+    @classmethod
+    def tearDownClass(cls) -> None:
+        cleanup_docker(containers=cls.containers, volumes=cls.volumes)
+
+    def _scalar(self, sql: str) -> str:
+        p = run(
+            [
+                "docker",
+                "exec",
+                self.pg_container,
+                "sh",
+                "-lc",
+                f'psql -U postgres -d appdb -t -A -c "{sql}"',
+            ]
+        )
+        return (p.stdout or "").strip()
+
+    def test_public_data_restored(self) -> None:
+        self.assertEqual(self._scalar("SELECT v FROM public.t WHERE id=1;"), "ok")
+
+    def test_view_restored(self) -> None:
+        self.assertEqual(self._scalar("SELECT count(*) FROM public.t_view;"), "1")
+
+    def test_non_public_schema_restored(self) -> None:
+        self.assertEqual(
+            self._scalar(
+                "SELECT count(*) FROM pg_namespace WHERE nspname='discourse_functions';"
+            ),
+            "1",
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()