skip gc tables handling if there is no gc table to restore

Author: plaharanne

crate/operator/restore_backup.py

@@ -1186,6 +1186,11 @@ async def set_gc_tables(
 
         if restore_type == SnapshotRestoreType.TABLES.value and tables is not None:
             gc_tables = [table for table in tables if table.startswith("gc.")]
+
+            # There is no gc table to restore, no need to proceed further
+            if not gc_tables:
+                return
+
             tables_str = ",".join(f"'{table}'" for table in gc_tables)
             where_stmt = f"t IN ({tables_str})"
         else:
@@ -1237,7 +1242,7 @@ async def rename_duplicated_tables(self):
         If the snapshot contains grand central tables, rename them if they exist
         in the cluster in order to recreate the new ones from the snapshot.
         """
-        if not self.gc_tables:
+        if not self.is_enabled():
             return
 
         try:
@@ -1259,7 +1264,7 @@ async def restore_tables(self):
         If the restore operation failed, rename back the gc tables
         to their original names.
         """
-        if not self.gc_tables:
+        if not self.is_enabled():
             return
 
         try:
@@ -1280,7 +1285,7 @@ async def cleanup_tables(self):
         """
         After a successful restore, the temporary renamed gc tables can be dropped.
         """
-        if not self.gc_tables:
+        if not self.is_enabled():
             return
 
         try:

tests/test_restore_backup.py

@@ -1100,8 +1100,10 @@ async def test_set_gc_tables(
         replace_gc_tables_data
     )
 
-    fetch_response = [(t,) for t in tables_with_schema]
-    mock_cursor.fetchall.return_value = fetch_response if gc_enabled else []
+    mock_cursor.fetchall.side_effect = [
+        [(t,) for t in tables_with_schema] if gc_enabled else [],
+        [(t,) for t in tables] if gc_enabled else [],
+    ]
 
     await gc_tables_cls.set_gc_tables(restore_type.value, tables_with_schema)
 
@@ -1118,6 +1120,8 @@ async def test_set_gc_tables(
                 (repository, snapshot),
             ),
         ]
+        if gc_enabled:
+            stmts.append(mock.call('SHOW TABLES FROM "gc";'))
         assert gc_tables_cls.gc_tables == (tables_with_schema if gc_enabled else [])
     elif restore_type == SnapshotRestoreType.TABLES:
         stmts = [
@@ -1132,6 +1136,8 @@ async def test_set_gc_tables(
                 (repository, snapshot),
             ),
         ]
+        if gc_enabled:
+            stmts.append(mock.call('SHOW TABLES FROM "gc";'))
         assert gc_tables_cls.gc_tables == (tables_with_schema if gc_enabled else [])
     else:
         stmts = []