mediagoblin/db/util.py

   1 # GNU MediaGoblin -- federated, autonomous media hosting
   2 # Copyright (C) 2011 Free Software Foundation, Inc
   3 #
   4 # This program is free software: you can redistribute it and/or modify
   5 # it under the terms of the GNU Affero General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU Affero General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU Affero General Public License
  15 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 """
  18 Utilities for database operations.
  19
  20 Some note on migration and indexing tools:
  21
  22 We store information about what the state of the database is in the
  23 'mediagoblin' document of the 'app_metadata' collection.  Keys in that
  24 document relevant to here:
  25
  26  - 'migration_number': The integer representing the current state of
  27    the migrations
  28 """
  29
  30 import copy
  31
  32 # Imports that other modules might use
  33 from pymongo import DESCENDING
  34 from pymongo.errors import InvalidId
  35 from mongokit import ObjectId
  36
  37 from mediagoblin.db.indexes import ACTIVE_INDEXES, DEPRECATED_INDEXES
  38
  39
  40 def add_new_indexes(database, active_indexes=ACTIVE_INDEXES):
  41     """
  42     Add any new indexes to the database.
  43
  44     Args:
  45      - database: pymongo or mongokit database instance.
  46      - active_indexes: indexes to possibly add in the pattern of:
  47        {'collection_name': {
  48             'identifier': {
  49                 'index': [index_foo_goes_here],
  50                 'unique': True}}
  51        where 'index' is the index to add and all other options are
  52        arguments for collection.create_index.
  53
  54     Returns:
  55       A list of indexes added in form ('collection', 'index_name')
  56     """
  57     indexes_added = []
  58
  59     for collection_name, indexes in active_indexes.iteritems():
  60         collection = database[collection_name]
  61         collection_indexes = collection.index_information().keys()
  62
  63         for index_name, index_data in indexes.iteritems():
  64             if not index_name in collection_indexes:
  65                 # Get a copy actually so we don't modify the actual
  66                 # structure
  67                 index_data = copy.copy(index_data)
  68                 index = index_data.pop('index')
  69                 collection.create_index(
  70                     index, name=index_name, **index_data)
  71
  72                 indexes_added.append((collection_name, index_name))
  73
  74     return indexes_added
  75
  76
  77 def remove_deprecated_indexes(database, deprecated_indexes=DEPRECATED_INDEXES):
  78     """
  79     Remove any deprecated indexes from the database.
  80
  81     Args:
  82      - database: pymongo or mongokit database instance.
  83      - deprecated_indexes: the indexes to deprecate in the pattern of:
  84        {'collection': ['index_identifier1', 'index_identifier2']}
  85
  86     Returns:
  87       A list of indexes removed in form ('collection', 'index_name')
  88     """
  89     indexes_removed = []
  90
  91     for collection_name, index_names in deprecated_indexes.iteritems():
  92         collection = database[collection_name]
  93         collection_indexes = collection.index_information().keys()
  94
  95         for index_name in index_names:
  96             if index_name in collection_indexes:
  97                 collection.drop_index(index_name)
  98
  99                 indexes_removed.append((collection_name, index_name))
 100
 101     return indexes_removed