when adding Tiger data, check first if database is in frozen state

nominatim/tools/freeze.py

@@ -50,3 +50,9 @@ def drop_flatnode_file(fpath: Optional[Path]) -> None:
     """
     if fpath and fpath.exists():
         fpath.unlink()
+
+def is_frozen(conn: Connection) -> bool:
+    """ Returns true if database is in a frozen state
+    """
+
+    return conn.table_exists('place') is False

nominatim/tools/tiger_data.py

@@ -23,6 +23,7 @@ from nominatim.db.sql_preprocessor import SQLPreprocessor
 from nominatim.errors import UsageError
 from nominatim.data.place_info import PlaceInfo
 from nominatim.tokenizer.base import AbstractAnalyzer, AbstractTokenizer
+from nominatim.tools import freeze
 
 LOG = logging.getLogger()
 
@@ -113,6 +114,13 @@ def add_tiger_data(data_dir: str, config: Configuration, threads: int,
     """
     dsn = config.get_libpq_dsn()
 
+    with connect(dsn) as conn:
+        is_frozen = freeze.is_frozen(conn)
+        conn.close()
+
+        if is_frozen:
+            raise UsageError("Tiger cannot be imported when database frozen (Github issue #3048)")
+
     with TigerInput(data_dir) as tar:
         if not tar:
             return 1