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don't create extra index on _types (fix #222)

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mongodb will use an index that begins with _types to service queries
against _types, so the extra index is only needed if no other fields are
indexed in the document. to be safe, we explicitly check all indexes to
see if any begins with _types, and only then prevent creation of the
additional index on _types.
This commit is contained in:
Dan Crosta 2011-07-11 10:15:55 -04:00
parent 859de712b4
commit 0847687fd1
2 changed files with 26 additions and 6 deletions
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21
mongoengine/queryset.py
View File

@ -476,22 +476,39 @@ class QuerySet(object):
index_opts = self._document._meta.get('index_options', {})
index_types = self._document._meta.get('index_types', True)
# determine if an index which we are creating includes
# _type as its first field; if so, we can avoid creating
# an extra index on _type, as mongodb will use the existing
# index to service queries against _type
types_indexed = False
def includes_types(fields):
first_field = None
if len(fields):
if isinstance(fields[0], basestring):
first_field = fields[0]
elif isinstance(fields[0], (list, tuple)) and len(fields[0]):
first_field = fields[0][0]
return first_field == '_types'
# Ensure indexes created by uniqueness constraints
for index in self._document._meta['unique_indexes']:
types_indexed = types_indexed or includes_types(index)
self._collection.ensure_index(index, unique=True,
background=background, drop_dups=drop_dups, **index_opts)
# Ensure document-defined indexes are created
if self._document._meta['indexes']:
for spec in self._document._meta['indexes']:
types_indexed = types_indexed or includes_types(spec['fields'])
opts = index_opts.copy()
opts['unique'] = spec.get('unique', False)
opts['sparse'] = spec.get('sparse', False)
self._collection.ensure_index(spec['fields'],
background=background, **opts)
# If _types is being used (for polymorphism), it needs an index
if index_types and '_types' in self._query:
# If _types is being used (for polymorphism), it needs an index,
# only if another index doesn't begin with _types
if index_types and '_types' in self._query and not types_indexed:
self._collection.ensure_index('_types',
background=background, **index_opts)

11
tests/document.py
View File

@ -397,7 +397,7 @@ class DocumentTest(unittest.TestCase):
info = collection.index_information()
info = [value['key'] for key, value in info.iteritems()]
self.assertEquals([[(u'_id', 1)], [(u'_types', 1)], [(u'_types', 1), (u'name', 1)]], info)
self.assertEquals([[(u'_id', 1)], [(u'_types', 1), (u'name', 1)]], info)
# Turn off inheritance
class Animal(Document):
@ -415,7 +415,7 @@ class DocumentTest(unittest.TestCase):
info = collection.index_information()
info = [value['key'] for key, value in info.iteritems()]
self.assertEquals([[(u'_id', 1)], [(u'_types', 1)], [(u'_types', 1), (u'name', 1)]], info)
self.assertEquals([[(u'_id', 1)], [(u'_types', 1), (u'name', 1)]], info)
info = collection.index_information()
indexes_to_drop = [key for key, value in info.iteritems() if '_types' in dict(value['key'])]
@ -601,8 +601,11 @@ class DocumentTest(unittest.TestCase):
BlogPost.drop_collection()
info = BlogPost.objects._collection.index_information()
# _id, types, '-date', 'tags', ('cat', 'date')
self.assertEqual(len(info), 5)
# _id, '-date', 'tags', ('cat', 'date')
# NB: there is no index on _types by itself, since
# the indices on -date and tags will both contain
# _types as first element in the key
self.assertEqual(len(info), 4)
# Indexes are lazy so use list() to perform query
list(BlogPost.objects)