split code into submodules

src/nominatim_db/tools/freeze.py

@@ -0,0 +1,58 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2024 by the Nominatim developer community.
+# For a full list of authors see the git log.
+"""
+Functions for removing unnecessary data from the database.
+"""
+from typing import Optional
+from pathlib import Path
+
+from psycopg2 import sql as pysql
+
+from nominatim_core.db.connection import Connection
+
+UPDATE_TABLES = [
+    'address_levels',
+    'gb_postcode',
+    'import_osmosis_log',
+    'import_polygon_%',
+    'location_area%',
+    'location_road%',
+    'place',
+    'planet_osm_%',
+    'search_name_%',
+    'us_postcode',
+    'wikipedia_%'
+]
+
+def drop_update_tables(conn: Connection) -> None:
+    """ Drop all tables only necessary for updating the database from
+        OSM replication data.
+    """
+    parts = (pysql.SQL("(tablename LIKE {})").format(pysql.Literal(t)) for t in UPDATE_TABLES)
+
+    with conn.cursor() as cur:
+        cur.execute(pysql.SQL("SELECT tablename FROM pg_tables WHERE ")
+                    + pysql.SQL(' or ').join(parts))
+        tables = [r[0] for r in cur]
+
+        for table in tables:
+            cur.drop_table(table, cascade=True)
+
+    conn.commit()
+
+
+def drop_flatnode_file(fpath: Optional[Path]) -> None:
+    """ Remove the flatnode file if it exists.
+    """
+    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