db: create indexes on fields we are going to use in filters

Indexes will be created in the "background": read / write operations
are allowed on the documents of the collection, while the new indexes
are being built.

At the same time, one can't drop a collection, while an index build
is in progress, thus, replace all drop()'s in tests with remove()'s,
so that we don't drop the collection between tests and don't have
to rebuild indexes again.

tests/resources/test_snippets.py

@@ -46,7 +46,7 @@ class TestSnippets(metaclass=AIOTestMeta):
     async def test_get_no_snippets(self):
         app = create_app(self.conf)
 
-        await app['db'].snippets.drop()
+        await app['db'].snippets.remove()
 
         async with AIOTestApp(app) as testapp:
             resp = await testapp.get('/snippets')
@@ -57,7 +57,7 @@ async def test_get_no_snippets(self):
     async def test_get_snippets(self):
         app = create_app(self.conf)
 
-        await app['db'].snippets.drop()
+        await app['db'].snippets.remove()
         await app['db'].snippets.insert(self.snippets)
 
         async with AIOTestApp(app) as testapp:
@@ -69,7 +69,7 @@ async def test_get_snippets(self):
     async def test_post_snippet(self):
         app = create_app(self.conf)
 
-        await app['db'].snippets.drop()
+        await app['db'].snippets.remove()
 
         async with AIOTestApp(app) as testapp:
             snippet = copy.deepcopy(self.snippets[0])
@@ -91,3 +91,13 @@ async def test_post_snippet(self):
             )
 
             assert snippet_resp == snippet_db
+
+    async def test_data_model_indexes_exist(self):
+        app = create_app(self.conf)
+
+        res = await app['db'].snippets.index_information()
+
+        assert res['author_idx']['key'] == [('author_id', 1)]
+        assert res['tags_idx']['key'] == [('tags', 1)]
+        assert res['updated_idx']['key'] == [('updated_at', -1)]
+        assert res['created_idx']['key'] == [('created_at', -1)]

xsnippet_api/database.py

@@ -13,6 +13,7 @@
 
 from motor.motor_asyncio import AsyncIOMotorClient
 from pymongo.son_manipulator import SONManipulator
+import pymongo
 
 
 def create_connection(conf, loop=None):
@@ -44,6 +45,21 @@ def create_connection(conf, loop=None):
     # is doing this implicitly for us on application level.
     db.add_son_manipulator(_AutoincrementId())
 
+    # ensure necessary indexes exist. background=True allows operations
+    # read/write operations on collections while indexes are being built
+    db.snippets.create_index('author_id',
+                             name='author_idx',
+                             background=True)
+    db.snippets.create_index('tags',
+                             name='tags_idx',
+                             background=True),
+    db.snippets.create_index([('created_at', pymongo.DESCENDING)],
+                             name='created_idx',
+                             background=True)
+    db.snippets.create_index([('updated_at', pymongo.DESCENDING)],
+                             name='updated_idx',
+                             background=True)
+
     return db