Home | History | Annotate | Download | only in database 
      1 TABLE_TYPE = object()
      2 VIEW_TYPE = object()
      3 
      4 
      5 class NameMissingException(Exception):
      6     pass
      7 
      8 
      9 def drop_views(manager, views):
     10     """
     11     Drops the specified views from the database
     12 
     13     If a specified view does not exist in the database, this method fails
     14     without modification
     15 
     16     @param manager the migration manager
     17     @param views the views to drop
     18     """
     19     check_exists(manager, views, VIEW_TYPE)
     20     for view in views:
     21         manager.execute('DROP VIEW `%s`' % view)
     22 
     23 
     24 def rename(manager, mapping):
     25     """
     26     Renames specified tables in the database
     27 
     28     Use this to rename a specified set of tables in a database. If a source in
     29     the mapping does not exist, this method fails without modification.
     30 
     31     @param manager the migration manager
     32     @param mapping a dictionary of orig_name => new_name. Any table not matching
     33                    an entry in this dictionary will not be renamed
     34     """
     35     check_exists(manager, (table for table, _ in mapping.iteritems()),
     36                   TABLE_TYPE)
     37     for orig_name, new_name in mapping.iteritems():
     38         manager.execute('RENAME TABLE `%s` TO `%s`' % (orig_name, new_name))
     39 
     40 
     41 def move_tables(manager, src_manager, tables):
     42     """
     43     Moves the specified tables from another database
     44 
     45     If a table does not exist in the source database, this method fails without
     46     modification
     47 
     48     @param manager the migration manager
     49     @param src_manager a migration manager that handles the source database
     50     @param tables a list of tables to move
     51     """
     52     check_exists(src_manager, tables, TABLE_TYPE)
     53     for table in tables:
     54         manager.execute('RENAME TABLE `%(db)s`.`%(table)s` TO `%(table)s`'
     55                         % dict(db=src_manager.get_db_name(), table=table))
     56 
     57 
     58 def drop_database(manager):
     59     """
     60     Drops the database that the specified manager controls
     61 
     62     @param manager the migration manager
     63     """
     64     manager.execute('DROP DATABASE `%s`' % manager.get_db_name())
     65 
     66 
     67 def check_exists(manager, names, type):
     68     """
     69     Checks if the tables or views exists.
     70 
     71     Raise an Exception if any of the names do not exist
     72 
     73     @param manager the migration manager
     74     @param names the table/view names
     75     @param type one of 'TABLE' or 'VIEW'
     76     """
     77     if type == TABLE_TYPE:
     78         info_table = 'TABLES'
     79     elif type == VIEW_TYPE:
     80         info_table = 'VIEWS'
     81     else:
     82         raise Exception("type parameter must be either TABLE_TYPE or VIEW_TYPE")
     83 
     84     query = ('SELECT table_name FROM information_schema.%s '
     85              'WHERE table_schema = %%s' % info_table)
     86     rows = manager.execute(query, manager.get_db_name())
     87     existing_names = [row[0] for row in rows]
     88 
     89     for name in names:
     90         if name not in existing_names:
     91             raise NameMissingException(
     92                     '%s missing from database, stopping' % name)
     93 
     94 
     95 def check_index_exists(manager, table_name, index_name):
     96     """
     97     Checks if a particular index exists on the table
     98 
     99     @param manager the migration manager
    100     @param table_name the table to check
    101     @param index_name the index to check
    102     """
    103     query = ('SELECT 1 FROM information_schema.statistics '
    104              'WHERE table_schema = %s AND table_name = %s AND index_name = %s')
    105     rows = manager.execute(query, manager.get_db_name(), table_name, index_name)
    106     return bool(rows)
    107 
    108 
    109 DJANGO_AUTH_TABLES = ('auth_group', 'auth_group_permissions', 'auth_permission')
    110 
    111 def auth_tables_exist(manager):
    112     try:
    113         check_exists(manager, DJANGO_AUTH_TABLES, TABLE_TYPE)
    114         return True
    115     except NameMissingException:
    116         return False
    117