swh.loader.tar.db: Remove dead code

swh/loader/tar/db.py

-# Copyright (C) 2015  The Software Heritage developers
-# See the AUTHORS file at the top-level directory of this distribution
-# License: GNU General Public License version 3, or any later version
-# See top-level LICENSE file for more information
-
-import psycopg2
-
-
-def connect(db_url):
-    """Open db connection.
-    """
-    return psycopg2.connect(db_url)
-
-
-def execute(cur, query_params):
-    """Execute the query_params.
-    query_params is expected to be either:
-    - a sql query (string)
-    - a tuple (sql query, params)
-    """
-    if isinstance(query_params, str):
-        cur.execute(query_params)
-    else:
-        cur.execute(*query_params)
-
-
-def entry_to_bytes(entry):
-    """Convert an entry coming from the database to bytes"""
-    if isinstance(entry, memoryview):
-        return entry.tobytes()
-    return entry
-
-
-def line_to_bytes(line):
-    """Convert a line coming from the database to bytes"""
-    return line.__class__(entry_to_bytes(entry) for entry in line)
-
-
-def cursor_to_bytes(cursor):
-    """Yield all the data from a cursor as bytes"""
-    yield from (line_to_bytes(line) for line in cursor)
-
-
-def query_fetch(db_conn, query_params):
-    """Execute sql query which returns results.
-    query_params is expected to be either:
-    - a sql query (string)
-    - a tuple (sql query, params)
-    """
-    with db_conn.cursor() as cur:
-        execute(cur, query_params)
-        yield from cursor_to_bytes(cur)