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 ASCENDING, 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_name': {
  85             'identifier': {
  86                 'index': [index_foo_goes_here],
  87                 'unique': True}}
  88
  89        (... although we really only need the 'identifier' here, as the
  90        rest of the information isn't used in this case.  But it's kept
  91        around so we can remember what it was)
  92
  93     Returns:
  94       A list of indexes removed in form ('collection', 'index_name')
  95     """
  96     indexes_removed = []
  97
  98     for collection_name, indexes in deprecated_indexes.iteritems():
  99         collection = database[collection_name]
 100         collection_indexes = collection.index_information().keys()
 101
 102         for index_name, index_data in indexes.iteritems():
 103             if index_name in collection_indexes:
 104                 collection.drop_index(index_name)
 105
 106                 indexes_removed.append((collection_name, index_name))
 107
 108     return indexes_removed