diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 73cfd9147c..f665a21518 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -17,6 +17,11 @@ Common: Switch from mitx.db to edx.db for sqlite databases. This will effectivel
   reset state for local instances of the code, unless you manually rename your
   mitx.db file to edx.db.
 
+Common: significant performance improvement for authorization checks and location translations.
+  Ensure all auth checks, check all possible permutations of the auth key (Instructor dashboard
+  now shows when it should for all courses in lms).
+  Made queries for Studio dashboard 2 orders of magnitude faster (and fewer).
+
 Blades: Video Transcripts: Fix clear and download buttons. BLD-438.
 
 Common: Switch over from MITX_FEATURES to just FEATURES. To override items in
diff --git a/cms/djangoapps/auth/authz.py b/cms/djangoapps/auth/authz.py
index a5d00e14c1..19c00f832a 100644
--- a/cms/djangoapps/auth/authz.py
+++ b/cms/djangoapps/auth/authz.py
@@ -63,7 +63,7 @@ def get_all_course_role_groupnames(location, role, use_filter=True):
     # filter to the ones which exist
     default = groupnames[0]
     if use_filter:
-        groupnames = [group for group in groupnames if Group.objects.filter(name=group).exists()]
+        groupnames = [group.name for group in Group.objects.filter(name__in=groupnames)]
     return groupnames, default
 
 
@@ -203,12 +203,8 @@ def remove_user_from_course_group(caller, user, location, role):
 
     # see if the user is actually in that role, if not then we don't have to do anything
     groupnames, _ = get_all_course_role_groupnames(location, role)
-    for groupname in groupnames:
-        groups = user.groups.filter(name=groupname)
-        if groups:
-            # will only be one with that name
-            user.groups.remove(groups[0])
-            user.save()
+    user.groups.remove(*user.groups.filter(name__in=groupnames))
+    user.save()
 
 
 def remove_user_from_creator_group(caller, user):
@@ -243,7 +239,7 @@ def is_user_in_course_group_role(user, location, role, check_staff=True):
         if check_staff and user.is_staff:
             return True
         groupnames, _ = get_all_course_role_groupnames(location, role)
-        return any(user.groups.filter(name=groupname).exists() for groupname in groupnames)
+        return user.groups.filter(name__in=groupnames).exists()
 
     return False
 
@@ -266,7 +262,7 @@ def is_user_in_creator_group(user):
 
     # Feature flag for using the creator group setting. Will be removed once the feature is complete.
     if settings.FEATURES.get('ENABLE_CREATOR_GROUP', False):
-        return user.groups.filter(name=COURSE_CREATOR_GROUP_NAME).count() > 0
+        return user.groups.filter(name=COURSE_CREATOR_GROUP_NAME).exists()
 
     return True
 
diff --git a/cms/djangoapps/contentstore/tests/test_contentstore.py b/cms/djangoapps/contentstore/tests/test_contentstore.py
index 563c05affb..a13742d404 100644
--- a/cms/djangoapps/contentstore/tests/test_contentstore.py
+++ b/cms/djangoapps/contentstore/tests/test_contentstore.py
@@ -7,7 +7,6 @@ from textwrap import dedent
 
 from django.test.utils import override_settings
 from django.conf import settings
-from django.core.urlresolvers import reverse
 from path import path
 from tempdir import mkdtemp_clean
 from fs.osfs import OSFS
@@ -427,7 +426,7 @@ class ContentStoreToyCourseTest(ModuleStoreTestCase):
 
         course = module_store.get_item(course_location)
         num_tabs = len(course.tabs)
-        last_tab = course.tabs[num_tabs - 1]
+        last_tab = course.tabs[-1]
         url_slug = last_tab['url_slug']
         delete_url = self._get_tab_locator(course, last_tab).url_reverse('xblock')
 
@@ -446,7 +445,7 @@ class ContentStoreToyCourseTest(ModuleStoreTestCase):
 
     def _get_tab_locator(self, course, tab):
         """ Returns the locator for a given tab. """
-        tab_location = 'i4x://MITx/999/static_tab/{0}'.format(tab['url_slug'])
+        tab_location = 'i4x://edX/999/static_tab/{0}'.format(tab['url_slug'])
         return loc_mapper().translate_location(
             course.location.course_id, Location(tab_location), False, True
         )
diff --git a/cms/djangoapps/contentstore/views/course.py b/cms/djangoapps/contentstore/views/course.py
index 32538a80c7..261370b7ff 100644
--- a/cms/djangoapps/contentstore/views/course.py
+++ b/cms/djangoapps/contentstore/views/course.py
@@ -128,7 +128,8 @@ def course_listing(request):
     """
     List all courses available to the logged in user
     """
-    courses = modulestore('direct').get_items(Location('i4x', None, None, 'course', None))
+    # there's an index on category which will be used if none of its antecedents are set
+    courses = modulestore('direct').get_items(Location(None, None, None, 'course', None))
 
     # filter out courses that we don't have access too
     def course_filter(course):
diff --git a/cms/envs/dev.py b/cms/envs/dev.py
index 74561cee63..0ca4266f40 100644
--- a/cms/envs/dev.py
+++ b/cms/envs/dev.py
@@ -129,7 +129,12 @@ CACHES = {
         'LOCATION': '/var/tmp/mongo_metadata_inheritance',
         'TIMEOUT': 300,
         'KEY_FUNCTION': 'util.memcache.safe_key',
-    }
+    },
+    'loc_cache': {
+        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
+        'LOCATION': 'edx_location_mem_cache',
+    },
+
 }
 
 # Make the keyedcache startup warnings go away
diff --git a/cms/envs/test.py b/cms/envs/test.py
index a35824ed52..e541b0d390 100644
--- a/cms/envs/test.py
+++ b/cms/envs/test.py
@@ -138,7 +138,12 @@ CACHES = {
         'LOCATION': '/var/tmp/mongo_metadata_inheritance',
         'TIMEOUT': 300,
         'KEY_FUNCTION': 'util.memcache.safe_key',
-    }
+    },
+    'loc_cache': {
+        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
+        'LOCATION': 'edx_location_mem_cache',
+    },
+
 }
 
 # hide ratelimit warnings while running tests
diff --git a/common/lib/xmodule/xmodule/modulestore/django.py b/common/lib/xmodule/xmodule/modulestore/django.py
index 42372ab64f..ef4b9df40a 100644
--- a/common/lib/xmodule/xmodule/modulestore/django.py
+++ b/common/lib/xmodule/xmodule/modulestore/django.py
@@ -129,8 +129,12 @@ def loc_mapper():
     global _loc_singleton
     # pylint: disable=W0212
     if _loc_singleton is None:
+        try:
+            loc_cache = get_cache('loc_cache')
+        except InvalidCacheBackendError:
+            loc_cache = get_cache('default')
         # instantiate
-        _loc_singleton = LocMapperStore(**settings.DOC_STORE_CONFIG)
+        _loc_singleton = LocMapperStore(loc_cache, **settings.DOC_STORE_CONFIG)
     # inject into split mongo modulestore
     if 'split' in _MODULESTORES:
         _MODULESTORES['split'].loc_mapper = _loc_singleton
diff --git a/common/lib/xmodule/xmodule/modulestore/loc_mapper_store.py b/common/lib/xmodule/xmodule/modulestore/loc_mapper_store.py
index c7355c2f29..31e56da140 100644
--- a/common/lib/xmodule/xmodule/modulestore/loc_mapper_store.py
+++ b/common/lib/xmodule/xmodule/modulestore/loc_mapper_store.py
@@ -4,10 +4,10 @@ Method for converting among our differing Location/Locator whatever reprs
 from random import randint
 import re
 import pymongo
+import bson.son
 
 from xmodule.modulestore.exceptions import InvalidLocationError, ItemNotFoundError, DuplicateItemError
 from xmodule.modulestore.locator import BlockUsageLocator
-from xmodule.modulestore.mongo import draft
 from xmodule.modulestore import Location
 import urllib
 
@@ -28,7 +28,7 @@ class LocMapperStore(object):
     '''
 
     def __init__(
-        self, host, db, collection, port=27017, user=None, password=None,
+        self, cache, host, db, collection, port=27017, user=None, password=None,
         **kwargs
     ):
         '''
@@ -48,6 +48,7 @@ class LocMapperStore(object):
 
         self.location_map = self.db[collection + '.location_map']
         self.location_map.write_concern = {'w': 1}
+        self.cache = cache
 
     # location_map functions
     def create_map_entry(self, course_location, course_id=None, draft_branch='draft', prod_branch='published',
@@ -91,9 +92,10 @@ class LocMapperStore(object):
             else:
                 course_id = "{0.org}.{0.course}".format(course_location)
         # very like _interpret_location_id but w/o the _id
-        location_id = {'org': course_location.org, 'course': course_location.course}
-        if course_location.category == 'course':
-            location_id['name'] = course_location.name
+        location_id = self._construct_location_son(
+            course_location.org, course_location.course, 
+            course_location.name if course_location.category == 'course' else None
+        )
 
         self.location_map.insert({
             '_id': location_id,
@@ -127,26 +129,33 @@ class LocMapperStore(object):
         of locations including course.
         """
         location_id = self._interpret_location_course_id(old_style_course_id, location)
+        if old_style_course_id is None:
+            old_style_course_id = self._generate_location_course_id(location_id)
 
-        maps = self.location_map.find(location_id).sort('_id.name', pymongo.ASCENDING)
-        if maps.count() == 0:
+        cached_value = self._get_locator_from_cache(old_style_course_id, location, published)
+        if cached_value:
+            return cached_value
+
+
+        maps = self.location_map.find(location_id)
+        maps = list(maps)
+        if len(maps) == 0:
             if add_entry_if_missing:
                 # create a new map
-                course_location = location.replace(category='course', name=location_id['_id.name'])
+                course_location = location.replace(category='course', name=location_id['_id']['name'])
                 self.create_map_entry(course_location)
                 entry = self.location_map.find_one(location_id)
             else:
                 raise ItemNotFoundError()
-        elif maps.count() > 1:
-            # if more than one, prefer the one w/o a name if that exists. Otherwise, choose the first (alphabetically)
+        elif len(maps) == 1:
             entry = maps[0]
         else:
+            # find entry w/o name, if any; otherwise, pick arbitrary
             entry = maps[0]
-
-        if published:
-            branch = entry['prod_branch']
-        else:
-            branch = entry['draft_branch']
+            for item in maps:
+                if 'name' not in item['_id']:
+                    entry = item
+                    break
 
         usage_id = entry['block_map'].get(self._encode_for_mongo(location.name))
         if usage_id is None:
@@ -165,7 +174,18 @@ class LocMapperStore(object):
         else:
             raise InvalidLocationError()
 
-        return BlockUsageLocator(course_id=entry['course_id'], branch=branch, usage_id=usage_id)
+        published_usage = BlockUsageLocator(
+            course_id=entry['course_id'], branch=entry['prod_branch'], usage_id=usage_id)
+        draft_usage = BlockUsageLocator(
+            course_id=entry['course_id'], branch=entry['draft_branch'], usage_id=usage_id)
+        if published:
+            result = published_usage
+        else:
+            result = draft_usage
+
+        self._cache_location_map_entry(old_style_course_id, location, published_usage, draft_usage)
+        return result
+
 
     def translate_locator_to_location(self, locator, get_course=False):
         """
@@ -185,161 +205,51 @@ class LocMapperStore(object):
 
         :param locator: a BlockUsageLocator
         """
+        if get_course:
+            cached_value = self._get_course_location_from_cache(locator.course_id)
+        else:
+            cached_value = self._get_location_from_cache(locator)
+        if cached_value:
+            return cached_value
+
         # This does not require that the course exist in any modulestore
         # only that it has a mapping entry.
         maps = self.location_map.find({'course_id': locator.course_id})
         # look for one which maps to this block usage_id
         if maps.count() == 0:
             return None
+        result = None
         for candidate in maps:
+            old_course_id = self._generate_location_course_id(candidate['_id'])
             for old_name, cat_to_usage in candidate['block_map'].iteritems():
                 for category, usage_id in cat_to_usage.iteritems():
-                    if get_course:
-                        if category == 'course':
-                            return Location(
-                                'i4x',
-                                candidate['_id']['org'],
-                                candidate['_id']['course'],
-                                'course',
-                                self._decode_from_mongo(old_name),
-                                None)
-                    elif usage_id == locator.usage_id:
-                        # Always return revision=None because the
-                        # old draft module store wraps locations as draft before
-                        # trying to access things.
-                        return Location(
-                            'i4x',
-                            candidate['_id']['org'],
-                            candidate['_id']['course'],
-                            category,
-                            self._decode_from_mongo(old_name),
-                            None)
+                    # cache all entries and then figure out if we have the one we want
+                    # Always return revision=None because the
+                    # old draft module store wraps locations as draft before
+                    # trying to access things.
+                    location = Location(
+                        'i4x',
+                        candidate['_id']['org'],
+                        candidate['_id']['course'],
+                        category,
+                        self._decode_from_mongo(old_name),
+                        None)
+                    published_locator = BlockUsageLocator(
+                        candidate['course_id'], branch=candidate['prod_branch'], usage_id=usage_id
+                    )
+                    draft_locator = BlockUsageLocator(
+                        candidate['course_id'], branch=candidate['draft_branch'], usage_id=usage_id
+                    )
+                    self._cache_location_map_entry(old_course_id, location, published_locator, draft_locator)
+                    
+                    if get_course and category == 'course':
+                        result = location
+                    elif not get_course and usage_id == locator.usage_id:
+                        result = location
+            if result is not None:
+                return result
         return None
 
-    def add_block_location_translator(self, location, old_course_id=None, usage_id=None):
-        """
-        Similar to translate_location which adds an entry if none is found, but this cannot create a new
-        course mapping entry, only a block within such a mapping entry. If it finds no existing
-        course maps, it raises ItemNotFoundError.
-
-        In the case that there are more than one mapping record for the course identified by location, this
-        method adds the mapping to all matching records! (translate_location only adds to one)
-
-        It allows the caller to specify
-        the new-style usage_id for the target rather than having the translate concoct its own.
-        If the provided usage_id already exists in one of the found maps for the org/course, this function
-        raises DuplicateItemError unless the old item id == the new one.
-
-        If the caller does not provide a usage_id and there exists an entry in one of the course variants,
-        it will use that entry. If more than one variant uses conflicting entries, it will raise DuplicateItemError.
-
-        Returns the usage_id used in the mapping
-
-        :param location: a fully specified Location
-        :param old_course_id: the old-style org/course or org/course/run string (optional)
-        :param usage_id: the desired new block_id. If left as None, this will generate one as per translate_location
-        """
-        location_id = self._interpret_location_course_id(old_course_id, location)
-
-        maps = self.location_map.find(location_id)
-        if maps.count() == 0:
-            raise ItemNotFoundError()
-
-        # turn maps from cursor to list
-        map_list = list(maps)
-        encoded_location_name = self._encode_for_mongo(location.name)
-        # check whether there's already a usage_id for this location (and it agrees w/ any passed in or found)
-        for map_entry in map_list:
-            if (encoded_location_name in map_entry['block_map'] and
-                    location.category in map_entry['block_map'][encoded_location_name]):
-                if usage_id is None:
-                    usage_id = map_entry['block_map'][encoded_location_name][location.category]
-                elif usage_id != map_entry['block_map'][encoded_location_name][location.category]:
-                    raise DuplicateItemError(usage_id, self, 'location_map')
-
-        computed_usage_id = usage_id
-
-        # update the maps (and generate a usage_id if it's not been set yet)
-        for map_entry in map_list:
-            if computed_usage_id is None:
-                computed_usage_id = self._add_to_block_map(location, location_id, map_entry['block_map'])
-            elif (encoded_location_name not in map_entry['block_map'] or
-                    location.category not in map_entry['block_map'][encoded_location_name]):
-                alt_usage_id = self._verify_uniqueness(computed_usage_id, map_entry['block_map'])
-                if alt_usage_id != computed_usage_id:
-                    if usage_id is not None:
-                        raise DuplicateItemError(usage_id, self, 'location_map')
-                    else:
-                        # revise already set ones and add to remaining ones
-                        computed_usage_id = self.update_block_location_translator(
-                            location,
-                            alt_usage_id,
-                            old_course_id,
-                            True
-                        )
-
-                map_entry['block_map'].setdefault(encoded_location_name, {})[location.category] = computed_usage_id
-                self.location_map.update({'_id': map_entry['_id']}, {'$set': {'block_map': map_entry['block_map']}})
-
-        return computed_usage_id
-
-    def update_block_location_translator(self, location, usage_id, old_course_id=None, autogenerated_usage_id=False):
-        """
-        Update all existing maps from location's block to the new usage_id. Used for changing the usage_id,
-        thus the usage_id is required.
-
-        Returns the usage_id. (which is primarily useful in the case of autogenerated_usage_id)
-
-        :param location: a fully specified Location
-        :param usage_id: the desired new block_id.
-        :param old_course_id: the old-style org/course or org/course/run string (optional)
-        :param autogenerated_usage_id: a flag used mostly for internal calls to indicate that this usage_id
-        was autogenerated and thus can be overridden if it's not unique. If you set this flag, the stored
-        usage_id may not be the one you submitted.
-        """
-        location_id = self._interpret_location_course_id(old_course_id, location)
-
-        maps = self.location_map.find(location_id)
-        encoded_location_name = self._encode_for_mongo(location.name)
-        for map_entry in maps:
-            # handle noop of renaming to same name
-            if (encoded_location_name in map_entry['block_map'] and
-                    map_entry['block_map'][encoded_location_name].get(location.category) == usage_id):
-                continue
-            alt_usage_id = self._verify_uniqueness(usage_id, map_entry['block_map'])
-            if alt_usage_id != usage_id:
-                if autogenerated_usage_id:
-                    # revise already set ones and add to remaining ones
-                    usage_id = self.update_block_location_translator(location, alt_usage_id, old_course_id, True)
-                    return usage_id
-                else:
-                    raise DuplicateItemError(usage_id, self, 'location_map')
-
-            if location.category in map_entry['block_map'].setdefault(encoded_location_name, {}):
-                map_entry['block_map'][encoded_location_name][location.category] = usage_id
-                self.location_map.update({'_id': map_entry['_id']}, {'$set': {'block_map': map_entry['block_map']}})
-
-        return usage_id
-
-    def delete_block_location_translator(self, location, old_course_id=None):
-        """
-        Remove all existing maps from location's block.
-
-        :param location: a fully specified Location
-        :param old_course_id: the old-style org/course or org/course/run string (optional)
-        """
-        location_id = self._interpret_location_course_id(old_course_id, location)
-
-        maps = self.location_map.find(location_id)
-        encoded_location_name = self._encode_for_mongo(location.name)
-        for map_entry in maps:
-            if location.category in map_entry['block_map'].setdefault(encoded_location_name, {}):
-                if len(map_entry['block_map'][encoded_location_name]) == 1:
-                    del map_entry['block_map'][encoded_location_name]
-                else:
-                    del map_entry['block_map'][encoded_location_name][location.category]
-                self.location_map.update({'_id': map_entry['_id']}, {'$set': {'block_map': map_entry['block_map']}})
-
     def _add_to_block_map(self, location, location_id, block_map):
         '''add the given location to the block_map and persist it'''
         if self._block_id_is_guid(location.name):
@@ -357,7 +267,7 @@ class LocMapperStore(object):
 
     def _interpret_location_course_id(self, course_id, location):
         """
-        Take the old style course id (org/course/run) and return a dict for querying the mapping table.
+        Take the old style course id (org/course/run) and return a dict w/ a SON for querying the mapping table.
         If the course_id is empty, it uses location, but this may result in an inadequate id.
 
         :param course_id: old style 'org/course/run' id from Location.course_id where Location.category = 'course'
@@ -367,12 +277,35 @@ class LocMapperStore(object):
         if course_id:
             # re doesn't allow ?P<_id.org> and ilk
             matched = re.match(r'([^/]+)/([^/]+)/([^/]+)', course_id)
-            return dict(zip(['_id.org', '_id.course', '_id.name'], matched.groups()))
+            return {'_id': self._construct_location_son(*matched.groups())}
 
-        location_id = {'_id.org': location.org, '_id.course': location.course}
         if location.category == 'course':
-            location_id['_id.name'] = location.name
-        return location_id
+            return {'_id': self._construct_location_son(location.org, location.course, location.name)}
+        else:
+            return bson.son.SON([('_id.org', location.org), ('_id.course', location.course)])
+    
+    def _generate_location_course_id(self, entry_id):
+        """
+        Generate a Location course_id for the given entry's id
+        """
+        # strip id envelope if any
+        entry_id = entry_id.get('_id', entry_id)
+        if entry_id.get('name', False):
+            return '{0[org]}/{0[course]}/{0[name]}'.format(entry_id)
+        elif entry_id.get('_id.org', False):
+            # the odd format one
+            return '{0[_id.org]}/{0[_id.course]}'.format(entry_id)
+        else:
+            return '{0[org]}/{0[course]}'.format(entry_id)
+    
+    def _construct_location_son(self, org, course, name=None):
+        """
+        Construct the SON needed to repr the location for either a query or an insertion
+        """
+        if name:
+            return bson.son.SON([('org', org), ('course', course), ('name', name)])
+        else:
+            return bson.son.SON([('org', org), ('course', course)])
 
     def _block_id_is_guid(self, name):
         """
@@ -413,3 +346,41 @@ class LocMapperStore(object):
         """
         return urllib.unquote(fieldname)
 
+    def _get_locator_from_cache(self, old_course_id, location, published):
+        """
+        See if the location x published pair is in the cache. If so, return the mapped locator.
+        """
+        entry = self.cache.get('{}+{}'.format(old_course_id, location.url()))
+        if entry is not None:
+            if published:
+                return entry[0]
+            else:
+                return entry[1]
+        return None
+
+    def _get_location_from_cache(self, locator):
+        """
+        See if the locator is in the cache. If so, return the mapped location.
+        """
+        return self.cache.get(unicode(locator))
+
+    def _get_course_location_from_cache(self, locator_course_id):
+        """
+        See if the course_id is in the cache. If so, return the mapped location to the
+        course root.
+        """
+        return self.cache.get('courseId+{}'.format(locator_course_id))
+
+    def _cache_location_map_entry(self, old_course_id, location, published_usage, draft_usage):
+        """
+        Cache the mapping from location to the draft and published Locators in entry.
+        Also caches the inverse. If the location is category=='course', it caches it for
+        the get_course query
+        """
+        setmany = {}
+        if location.category == 'course':
+            setmany['courseId+{}'.format(published_usage.course_id)] = location
+        setmany[unicode(published_usage)] = location
+        setmany[unicode(draft_usage)] = location
+        setmany['{}+{}'.format(old_course_id, location.url())] = (published_usage, draft_usage)
+        self.cache.set_many(setmany)
diff --git a/common/lib/xmodule/xmodule/modulestore/tests/test_location_mapper.py b/common/lib/xmodule/xmodule/modulestore/tests/test_location_mapper.py
index 087a1951a9..18745bd856 100644
--- a/common/lib/xmodule/xmodule/modulestore/tests/test_location_mapper.py
+++ b/common/lib/xmodule/xmodule/modulestore/tests/test_location_mapper.py
@@ -7,8 +7,9 @@ import unittest
 import uuid
 from xmodule.modulestore import Location
 from xmodule.modulestore.locator import BlockUsageLocator
-from xmodule.modulestore.exceptions import ItemNotFoundError, DuplicateItemError
+from xmodule.modulestore.exceptions import ItemNotFoundError
 from xmodule.modulestore.loc_mapper_store import LocMapperStore
+from mock import Mock
 
 
 class TestLocationMapper(unittest.TestCase):
@@ -23,8 +24,10 @@ class TestLocationMapper(unittest.TestCase):
             'collection': 'modulestore{0}'.format(uuid.uuid4().hex[:5]),
         }
 
+        cache_standin = TrivialCache()
+        self.instrumented_cache = Mock(spec=cache_standin, wraps=cache_standin)
         # pylint: disable=W0142
-        TestLocationMapper.loc_store = LocMapperStore(**modulestore_options)
+        TestLocationMapper.loc_store = LocMapperStore(self.instrumented_cache, **modulestore_options)
 
     def tearDown(self):
         dbref = TestLocationMapper.loc_store.db
@@ -36,8 +39,9 @@ class TestLocationMapper(unittest.TestCase):
         org = 'foo_org'
         course = 'bar_course'
         loc_mapper().create_map_entry(Location('i4x', org, course, 'course', 'baz_run'))
+        # pylint: disable=protected-access
         entry = loc_mapper().location_map.find_one({
-            '_id': {'org': org, 'course': course, 'name': 'baz_run'}
+            '_id': loc_mapper()._construct_location_son(org, course, 'baz_run')
         })
         self.assertIsNotNone(entry, "Didn't find entry")
         self.assertEqual(entry['course_id'], '{}.{}.baz_run'.format(org, course))
@@ -48,8 +52,9 @@ class TestLocationMapper(unittest.TestCase):
         # ensure create_entry does the right thing when not given a course (creates org/course
         # rather than org/course/run course_id)
         loc_mapper().create_map_entry(Location('i4x', org, course, 'vertical', 'baz_vert'))
+        # find the one which has no name
         entry = loc_mapper().location_map.find_one({
-            '_id': {'org': org, 'course': course}
+            '_id' : loc_mapper()._construct_location_son(org, course, None)
         })
         self.assertIsNotNone(entry, "Didn't find entry")
         self.assertEqual(entry['course_id'], '{}.{}'.format(org, course))
@@ -63,15 +68,28 @@ class TestLocationMapper(unittest.TestCase):
             'wip',
             'live',
             block_map)
-        entry = loc_mapper().location_map.find_one({
-            '_id': {'org': org, 'course': course}
-        })
+        entry = loc_mapper().location_map.find_one({'_id.org': org, '_id.course': course})
         self.assertIsNotNone(entry, "Didn't find entry")
         self.assertEqual(entry['course_id'], 'foo_org.geek_dept.quux_course.baz_run')
         self.assertEqual(entry['draft_branch'], 'wip')
         self.assertEqual(entry['prod_branch'], 'live')
         self.assertEqual(entry['block_map'], block_map)
 
+
+    def translate_n_check(self, location, old_style_course_id, new_style_course_id, usage_id, branch, add_entry=False):
+        """
+        Request translation, check course_id, usage_id, and branch
+        """
+        prob_locator = loc_mapper().translate_location(
+            old_style_course_id, 
+            location, 
+            published= (branch=='published'),
+            add_entry_if_missing=add_entry
+        )
+        self.assertEqual(prob_locator.course_id, new_style_course_id)
+        self.assertEqual(prob_locator.usage_id, usage_id)
+        self.assertEqual(prob_locator.branch, branch)
+
     def test_translate_location_read_only(self):
         """
         Test the variants of translate_location which don't create entries, just decode
@@ -88,83 +106,67 @@ class TestLocationMapper(unittest.TestCase):
             )
 
         new_style_course_id = '{}.geek_dept.{}.baz_run'.format(org, course)
-        block_map = {'abc123': {'problem': 'problem2'}}
+        block_map = {
+            'abc123': {'problem': 'problem2'}, 
+            'def456': {'problem': 'problem4'},
+            'ghi789': {'problem': 'problem7'},
+        }
         loc_mapper().create_map_entry(
             Location('i4x', org, course, 'course', 'baz_run'),
             new_style_course_id,
             block_map=block_map
         )
+        test_problem_locn = Location('i4x', org, course, 'problem', 'abc123')
         # only one course matches
-        prob_locator = loc_mapper().translate_location(
-            old_style_course_id,
-            Location('i4x', org, course, 'problem', 'abc123'),
-            add_entry_if_missing=False
-        )
-        self.assertEqual(prob_locator.course_id, new_style_course_id)
-        self.assertEqual(prob_locator.branch, 'published')
-        self.assertEqual(prob_locator.usage_id, 'problem2')
-        # look for w/ only the Location (works b/c there's only one possible course match)
-        prob_locator = loc_mapper().translate_location(
-            None,
-            Location('i4x', org, course, 'problem', 'abc123'),
-            add_entry_if_missing=False
-        )
-        self.assertEqual(prob_locator.course_id, new_style_course_id)
+        self.translate_n_check(test_problem_locn, old_style_course_id, new_style_course_id, 'problem2', 'published')
+        # look for w/ only the Location (works b/c there's only one possible course match). Will force
+        # cache as default translation for this problemid
+        self.translate_n_check(test_problem_locn, None, new_style_course_id, 'problem2', 'published')
         # look for non-existent problem
         with self.assertRaises(ItemNotFoundError):
-            prob_locator = loc_mapper().translate_location(
+            loc_mapper().translate_location(
                 None,
                 Location('i4x', org, course, 'problem', '1def23'),
                 add_entry_if_missing=False
             )
 
-        # add a distractor course
-        block_map = {'abc123': {'problem': 'problem3'}}
+        # add a distractor course (note that abc123 has a different translation in this one)
+        distractor_block_map = {
+            'abc123': {'problem': 'problem3'}, 
+            'def456': {'problem': 'problem4'},
+            'ghi789': {'problem': 'problem7'},
+        }
+        test_delta_new_id = '{}.geek_dept.{}.{}'.format(org, course, 'delta_run')
+        test_delta_old_id = '{}/{}/{}'.format(org, course, 'delta_run')
         loc_mapper().create_map_entry(
             Location('i4x', org, course, 'course', 'delta_run'),
-            '{}.geek_dept.{}.{}'.format(org, course, 'delta_run'),
-            block_map=block_map
+            test_delta_new_id,
+            block_map=distractor_block_map
         )
-        prob_locator = loc_mapper().translate_location(
-            old_style_course_id,
-            Location('i4x', org, course, 'problem', 'abc123'),
-            add_entry_if_missing=False
-        )
-        self.assertEqual(prob_locator.course_id, new_style_course_id)
-        self.assertEqual(prob_locator.usage_id, 'problem2')
-        # look for w/ only the Location (not unique; so, just verify it returns something)
+        # test that old translation still works
+        self.translate_n_check(test_problem_locn, old_style_course_id, new_style_course_id, 'problem2', 'published')
+        # and new returns new id
+        self.translate_n_check(test_problem_locn, test_delta_old_id, test_delta_new_id, 'problem3', 'published')
+        # look for default translation of uncached Location (not unique; so, just verify it returns something)
         prob_locator = loc_mapper().translate_location(
             None,
-            Location('i4x', org, course, 'problem', 'abc123'),
+            Location('i4x', org, course, 'problem', 'def456'),
             add_entry_if_missing=False
         )
         self.assertIsNotNone(prob_locator, "couldn't find ambiguous location")
 
-        # add a default course pointing to the delta_run
+        # make delta_run default course: anything not cached using None as old_course_id will use this
         loc_mapper().create_map_entry(
             Location('i4x', org, course, 'problem', '789abc123efg456'),
-            '{}.geek_dept.{}.{}'.format(org, course, 'delta_run'),
+            test_delta_new_id,
             block_map=block_map
         )
-        # now the ambiguous query should return delta
-        prob_locator = loc_mapper().translate_location(
-            None,
-            Location('i4x', org, course, 'problem', 'abc123'),
-            add_entry_if_missing=False
-        )
-        self.assertEqual(prob_locator.course_id, '{}.geek_dept.{}.{}'.format(org, course, 'delta_run'))
-        self.assertEqual(prob_locator.usage_id, 'problem3')
+        # now an uncached ambiguous query should return delta
+        test_unused_locn = Location('i4x', org, course, 'problem', 'ghi789')
+        self.translate_n_check(test_unused_locn, None, test_delta_new_id, 'problem7', 'published')
 
         # get the draft one (I'm sorry this is getting long)
-        prob_locator = loc_mapper().translate_location(
-            None,
-            Location('i4x', org, course, 'problem', 'abc123'),
-            published=False,
-            add_entry_if_missing=False
-        )
-        self.assertEqual(prob_locator.course_id, '{}.geek_dept.{}.{}'.format(org, course, 'delta_run'))
-        self.assertEqual(prob_locator.usage_id, 'problem3')
-        self.assertEqual(prob_locator.branch, 'draft')
+        self.translate_n_check(test_unused_locn, None, test_delta_new_id, 'problem7', 'draft')
 
     def test_translate_location_dwim(self):
         """
@@ -176,48 +178,39 @@ class TestLocationMapper(unittest.TestCase):
         old_style_course_id = '{}/{}/{}'.format(org, course, 'baz_run')
         problem_name = 'abc123abc123abc123abc123abc123f9'
         location = Location('i4x', org, course, 'problem', problem_name)
-        prob_locator = loc_mapper().translate_location(
-            old_style_course_id,
-            location,
-            add_entry_if_missing=True
-        )
         new_style_course_id = '{}.{}.{}'.format(org, course, 'baz_run')
-        self.assertEqual(prob_locator.course_id, new_style_course_id)
-        self.assertEqual(prob_locator.branch, 'published')
-        self.assertEqual(prob_locator.usage_id, 'problemabc')
-        # look for w/ only the Location (works b/c there's only one possible course match)
-        prob_locator = loc_mapper().translate_location(
-            None,
-            location,
-            add_entry_if_missing=True
-        )
-        self.assertEqual(prob_locator.course_id, new_style_course_id)
+        self.translate_n_check(location, old_style_course_id, new_style_course_id, 'problemabc', 'published', True)
+        # look for w/ only the Location (works b/c there's only one possible course match): causes cache
+        self.translate_n_check(location, None, new_style_course_id, 'problemabc', 'published', True)
+
         # create an entry w/o a guid name
         other_location = Location('i4x', org, course, 'chapter', 'intro')
-        locator = loc_mapper().translate_location(
-            old_style_course_id,
-            other_location,
-            add_entry_if_missing=True
-        )
-        self.assertEqual(locator.usage_id, 'intro')
+        self.translate_n_check(other_location, old_style_course_id, new_style_course_id, 'intro', 'published', True)
 
         # add a distractor course
+        delta_new_course_id = '{}.geek_dept.{}.{}'.format(org, course, 'delta_run')
+        delta_course_locn = Location('i4x', org, course, 'course', 'delta_run')
         loc_mapper().create_map_entry(
-            Location('i4x', org, course, 'course', 'delta_run'),
-            '{}.geek_dept.{}.{}'.format(org, course, 'delta_run'),
+            delta_course_locn,
+            delta_new_course_id,
             block_map={problem_name: {'problem': 'problem3'}}
         )
-        prob_locator = loc_mapper().translate_location(
-            old_style_course_id,
-            location,
-            add_entry_if_missing=True
+        self.translate_n_check(location, old_style_course_id, new_style_course_id, 'problemabc', 'published', True)
+
+        # add a new one to both courses (ensure name doesn't have same beginning)
+        new_prob_name = uuid.uuid4().hex
+        while new_prob_name.startswith('abc'):
+            new_prob_name = uuid.uuid4().hex
+        new_prob_locn = location.replace(name=new_prob_name)
+        new_usage_id = 'problem{}'.format(new_prob_name[:3])
+        self.translate_n_check(new_prob_locn, old_style_course_id, new_style_course_id, new_usage_id, 'published', True)
+        self.translate_n_check(
+            new_prob_locn, delta_course_locn.course_id, delta_new_course_id, new_usage_id, 'published', True
         )
-        self.assertEqual(prob_locator.course_id, new_style_course_id)
-        self.assertEqual(prob_locator.usage_id, 'problemabc')
-        # look for w/ only the Location (not unique; so, just verify it returns something)
+        # look for w/ only the Location: causes caching and not unique; so, can't check which course
         prob_locator = loc_mapper().translate_location(
             None,
-            location,
+            new_prob_locn,
             add_entry_if_missing=True
         )
         self.assertIsNotNone(prob_locator, "couldn't find ambiguous location")
@@ -225,17 +218,20 @@ class TestLocationMapper(unittest.TestCase):
         # add a default course pointing to the delta_run
         loc_mapper().create_map_entry(
             Location('i4x', org, course, 'problem', '789abc123efg456'),
-            '{}.geek_dept.{}.{}'.format(org, course, 'delta_run'),
+            delta_new_course_id,
             block_map={problem_name: {'problem': 'problem3'}}
         )
         # now the ambiguous query should return delta
-        prob_locator = loc_mapper().translate_location(
-            None,
-            location,
-            add_entry_if_missing=False
+        again_prob_name = uuid.uuid4().hex
+        while again_prob_name.startswith('abc') or again_prob_name.startswith(new_prob_name[:3]):
+            again_prob_name = uuid.uuid4().hex
+        again_prob_locn = location.replace(name=again_prob_name)
+        again_usage_id = 'problem{}'.format(again_prob_name[:3])
+        self.translate_n_check(again_prob_locn, old_style_course_id, new_style_course_id, again_usage_id, 'published', True)
+        self.translate_n_check(
+            again_prob_locn, delta_course_locn.course_id, delta_new_course_id, again_usage_id, 'published', True
         )
-        self.assertEqual(prob_locator.course_id, '{}.geek_dept.{}.{}'.format(org, course, 'delta_run'))
-        self.assertEqual(prob_locator.usage_id, 'problem3')
+        self.translate_n_check(again_prob_locn, None, delta_new_course_id, again_usage_id, 'published', True)
 
     def test_translate_locator(self):
         """
@@ -352,185 +348,6 @@ class TestLocationMapper(unittest.TestCase):
         reverted_location = loc_mapper().translate_locator_to_location(prob_locator)
         self.assertEqual(location, reverted_location)
 
-    def test_add_block(self):
-        """
-        Test add_block_location_translator(location, old_course_id=None, usage_id=None)
-        """
-        # call w/ no matching courses
-        org = 'foo_org'
-        course = 'bar_course'
-        old_style_course_id = '{}/{}/{}'.format(org, course, 'baz_run')
-        problem_name = 'abc123abc123abc123abc123abc123f9'
-        location = Location('i4x', org, course, 'problem', problem_name)
-        with self.assertRaises(ItemNotFoundError):
-            loc_mapper().add_block_location_translator(location)
-        with self.assertRaises(ItemNotFoundError):
-            loc_mapper().add_block_location_translator(location, old_style_course_id)
-
-        # w/ one matching course
-        new_style_course_id = '{}.{}.{}'.format(org, course, 'baz_run')
-        loc_mapper().create_map_entry(
-            Location('i4x', org, course, 'course', 'baz_run'),
-            new_style_course_id,
-        )
-        new_usage_id = loc_mapper().add_block_location_translator(location)
-        self.assertEqual(new_usage_id, 'problemabc')
-        # look it up
-        translated_loc = loc_mapper().translate_location(old_style_course_id, location, add_entry_if_missing=False)
-        self.assertEqual(translated_loc.course_id, new_style_course_id)
-        self.assertEqual(translated_loc.usage_id, new_usage_id)
-
-        # w/ one distractor which has one entry already
-        new_style_course_id = '{}.geek_dept.{}.{}'.format(org, course, 'delta_run')
-        loc_mapper().create_map_entry(
-            Location('i4x', org, course, 'course', 'delta_run'),
-            new_style_course_id,
-            block_map={'48f23a10395384929234': {'chapter': 'chapter48f'}}
-        )
-        # try adding the one added before
-        new_usage_id2 = loc_mapper().add_block_location_translator(location)
-        self.assertEqual(new_usage_id, new_usage_id2)
-        # it should be in the distractor now
-        new_location = loc_mapper().translate_locator_to_location(
-            BlockUsageLocator(course_id=new_style_course_id, usage_id=new_usage_id2, branch='published')
-        )
-        self.assertEqual(new_location, location)
-        # add one close to the existing chapter (cause name collision)
-        location = Location('i4x', org, course, 'chapter', '48f23a103953849292341234567890ab')
-        new_usage_id = loc_mapper().add_block_location_translator(location)
-        self.assertRegexpMatches(new_usage_id, r'^chapter48f\d')
-        # retrievable from both courses
-        new_location = loc_mapper().translate_locator_to_location(
-            BlockUsageLocator(course_id=new_style_course_id, usage_id=new_usage_id, branch='published')
-        )
-        self.assertEqual(new_location, location)
-        new_location = loc_mapper().translate_locator_to_location(
-            BlockUsageLocator(
-                course_id='{}.{}.{}'.format(org, course, 'baz_run'),
-                usage_id=new_usage_id,
-                branch='published'
-            )
-        )
-        self.assertEqual(new_location, location)
-
-        # provoke duplicate item errors
-        location = location.replace(name='44f23a103953849292341234567890ab')
-        with self.assertRaises(DuplicateItemError):
-            loc_mapper().add_block_location_translator(location, usage_id=new_usage_id)
-        new_usage_id = loc_mapper().add_block_location_translator(location, old_course_id=old_style_course_id)
-        other_course_old_style = '{}/{}/{}'.format(org, course, 'delta_run')
-        new_usage_id2 = loc_mapper().add_block_location_translator(
-            location,
-            old_course_id=other_course_old_style,
-            usage_id='{}b'.format(new_usage_id)
-        )
-        with self.assertRaises(DuplicateItemError):
-            loc_mapper().add_block_location_translator(location)
-
-    def test_update_block(self):
-        """
-        test update_block_location_translator(location, usage_id, old_course_id=None)
-        """
-        org = 'foo_org'
-        course = 'bar_course'
-        new_style_course_id = '{}.geek_dept.{}.baz_run'.format(org, course)
-        loc_mapper().create_map_entry(
-            Location('i4x', org, course, 'course', 'baz_run'),
-            new_style_course_id,
-            block_map={
-                'abc123': {'problem': 'problem2'},
-                '48f23a10395384929234': {'chapter': 'chapter48f'},
-                '1': {'chapter': 'chapter1', 'problem': 'problem1'},
-            }
-        )
-        new_style_course_id2 = '{}.geek_dept.{}.delta_run'.format(org, course)
-        loc_mapper().create_map_entry(
-            Location('i4x', org, course, 'course', 'delta_run'),
-            new_style_course_id2,
-            block_map={
-                'abc123': {'problem': 'problem3'},
-                '48f23a10395384929234': {'chapter': 'chapter48b'},
-                '1': {'chapter': 'chapter2', 'problem': 'problem2'},
-            }
-        )
-        location = Location('i4x', org, course, 'problem', '1')
-        # change in all courses to same value
-        loc_mapper().update_block_location_translator(location, 'problem1')
-        trans_loc = loc_mapper().translate_locator_to_location(
-            BlockUsageLocator(course_id=new_style_course_id, usage_id='problem1', branch='published')
-        )
-        self.assertEqual(trans_loc, location)
-        trans_loc = loc_mapper().translate_locator_to_location(
-            BlockUsageLocator(course_id=new_style_course_id2, usage_id='problem1', branch='published')
-        )
-        self.assertEqual(trans_loc, location)
-        # try to change to overwrite used usage_id
-        location = Location('i4x', org, course, 'chapter', '48f23a10395384929234')
-        with self.assertRaises(DuplicateItemError):
-            loc_mapper().update_block_location_translator(location, 'chapter2')
-        # just change the one course
-        loc_mapper().update_block_location_translator(location, 'chapter2', '{}/{}/{}'.format(org, course, 'baz_run'))
-        trans_loc = loc_mapper().translate_locator_to_location(
-            BlockUsageLocator(course_id=new_style_course_id, usage_id='chapter2', branch='published')
-        )
-        self.assertEqual(trans_loc.name, '48f23a10395384929234')
-        # but this still points to the old
-        trans_loc = loc_mapper().translate_locator_to_location(
-            BlockUsageLocator(course_id=new_style_course_id2, usage_id='chapter2', branch='published')
-        )
-        self.assertEqual(trans_loc.name, '1')
-
-    def test_delete_block(self):
-        """
-        test delete_block_location_translator(location, old_course_id=None)
-        """
-        org = 'foo_org'
-        course = 'bar_course'
-        new_style_course_id = '{}.geek_dept.{}.baz_run'.format(org, course)
-        loc_mapper().create_map_entry(
-            Location('i4x', org, course, 'course', 'baz_run'),
-            new_style_course_id,
-            block_map={
-                'abc123': {'problem': 'problem2'},
-                '48f23a10395384929234': {'chapter': 'chapter48f'},
-                '1': {'chapter': 'chapter1', 'problem': 'problem1'},
-            }
-        )
-        new_style_course_id2 = '{}.geek_dept.{}.delta_run'.format(org, course)
-        loc_mapper().create_map_entry(
-            Location('i4x', org, course, 'course', 'delta_run'),
-            new_style_course_id2,
-            block_map={
-                'abc123': {'problem': 'problem3'},
-                '48f23a10395384929234': {'chapter': 'chapter48b'},
-                '1': {'chapter': 'chapter2', 'problem': 'problem2'},
-            }
-        )
-        location = Location('i4x', org, course, 'problem', '1')
-        # delete from all courses
-        loc_mapper().delete_block_location_translator(location)
-        self.assertIsNone(loc_mapper().translate_locator_to_location(
-            BlockUsageLocator(course_id=new_style_course_id, usage_id='problem1', branch='published')
-        ))
-        self.assertIsNone(loc_mapper().translate_locator_to_location(
-            BlockUsageLocator(course_id=new_style_course_id2, usage_id='problem2', branch='published')
-        ))
-        # delete from one course
-        location = location.replace(name='abc123')
-        loc_mapper().delete_block_location_translator(location, '{}/{}/{}'.format(org, course, 'baz_run'))
-        with self.assertRaises(ItemNotFoundError):
-            loc_mapper().translate_location(
-                '{}/{}/{}'.format(org, course, 'baz_run'),
-                location,
-                add_entry_if_missing=False
-            )
-        locator = loc_mapper().translate_location(
-            '{}/{}/{}'.format(org, course, 'delta_run'),
-            location,
-            add_entry_if_missing=False
-        )
-        self.assertEqual(locator.usage_id, 'problem3')
-
 
 #==================================
 # functions to mock existing services
@@ -545,3 +362,23 @@ def render_to_template_mock(*_args):
     """
     Mocks the mako render_to_template w/ a noop
     """
+
+
+class TrivialCache(object):
+    """
+    A trivial cache impl
+    """
+    def __init__(self):
+        self.cache = {}
+
+    def get(self, key):
+        """
+        Mock the .get
+        """
+        return self.cache.get(key)
+
+    def set_many(self, entries):
+        """
+        mock set_many
+        """
+        self.cache.update(entries)
diff --git a/common/lib/xmodule/xmodule/modulestore/tests/test_split_migrator.py b/common/lib/xmodule/xmodule/modulestore/tests/test_split_migrator.py
index 7ddab1e376..c444aa32e1 100644
--- a/common/lib/xmodule/xmodule/modulestore/tests/test_split_migrator.py
+++ b/common/lib/xmodule/xmodule/modulestore/tests/test_split_migrator.py
@@ -43,7 +43,10 @@ class TestMigration(unittest.TestCase):
 
     def setUp(self):
         super(TestMigration, self).setUp()
-        self.loc_mapper = LocMapperStore(**self.db_config)
+        noop_cache = mock.Mock(spec=['get', 'set_many'])
+        noop_cache.configure_mock(**{'get.return_value': None})
+        # pylint: disable=W0142
+        self.loc_mapper = LocMapperStore(noop_cache, **self.db_config)
         self.old_mongo = MongoModuleStore(self.db_config, **self.modulestore_options)
         self.draft_mongo = DraftModuleStore(self.db_config, **self.modulestore_options)
         self.split_mongo = SplitMongoModuleStore(
diff --git a/lms/djangoapps/courseware/roles.py b/lms/djangoapps/courseware/roles.py
index 110bb9f362..60853e8090 100644
--- a/lms/djangoapps/courseware/roles.py
+++ b/lms/djangoapps/courseware/roles.py
@@ -4,7 +4,6 @@ adding users, removing users, and listing members
 """
 
 from abc import ABCMeta, abstractmethod
-from functools import partial
 
 from django.contrib.auth.models import User, Group
 
diff --git a/lms/envs/dev.py b/lms/envs/dev.py
index bfff68157e..30053d3da3 100644
--- a/lms/envs/dev.py
+++ b/lms/envs/dev.py
@@ -85,7 +85,11 @@ CACHES = {
         'LOCATION': '/var/tmp/mongo_metadata_inheritance',
         'TIMEOUT': 300,
         'KEY_FUNCTION': 'util.memcache.safe_key',
-    }
+    },
+    'loc_cache': {
+        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
+        'LOCATION': 'edx_location_mem_cache',
+    },
 }
 
 
diff --git a/lms/envs/test.py b/lms/envs/test.py
index 6fe96d760b..2dbfca0bd6 100644
--- a/lms/envs/test.py
+++ b/lms/envs/test.py
@@ -165,7 +165,12 @@ CACHES = {
         'LOCATION': '/var/tmp/mongo_metadata_inheritance',
         'TIMEOUT': 300,
         'KEY_FUNCTION': 'util.memcache.safe_key',
-    }
+    },
+    'loc_cache': {
+        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
+        'LOCATION': 'edx_location_mem_cache',
+    },
+
 }
 
 # Dummy secret key for dev
diff --git a/mongo_indexes.md b/mongo_indexes.md
new file mode 100644
index 0000000000..f42aed9a58
--- /dev/null
+++ b/mongo_indexes.md
@@ -0,0 +1,21 @@
+These are the indexes each mongo db should have in order to perform well.
+Each section states the collection name and then the indexes. To create an index,
+you'll typically either use the mongohq type web interface or a standard terminal console.
+If a terminal, this assumes you've logged in and gotten to the mongo prompt 
+```
+mongo mydatabasename
+```
+
+If using the terminal, to add an index to a collection, you'll need to prefix ```ensureIndex``` with
+```
+db.collection_name
+```
+as in ```db.location_map.ensureIndex({'course_id': 1}{background: true})```
+
+location_map:
+=============
+
+```
+ensureIndex({'_id.org': 1, '_id.course': 1})
+ensureIndex({'course_id': 1})
+```