def migrate(engine):
    """Replace 'backend' with 'store' in meta_data column of image_locations"""
    sql_query = ("UPDATE image_locations SET meta_data = REPLACE(meta_data, "
                 "'\"backend\":', '\"store\":') where INSTR(meta_data, "
                 " '\"backend\":') > 0")

    # NOTE(abhishekk): INSTR function doesn't supported in postgresql
    if engine.name == 'postgresql':
        sql_query = ("UPDATE image_locations SET meta_data = REPLACE("
                     "meta_data, '\"backend\":', '\"store\":') where "
                     "POSITION('\"backend\":' IN meta_data) > 0")

    with engine.connect() as con:
        migrated_rows = con.execute(sql_query)
        return migrated_rows.rowcount