diff --git a/src/storage/sqlite.py b/src/storage/sqlite.py
index f4107241..438cbdcb 100644
--- a/src/storage/sqlite.py
+++ b/src/storage/sqlite.py
@@ -11,14 +11,18 @@ class SqliteInventory(InventoryStorage):
     def __init__(self):
         super(self.__class__, self).__init__()
         self._inventory = {} #of objects (like msg payloads and pubkey payloads) Does not include protocol headers (the first 24 bytes of each packet).
-        self._streams = collections.defaultdict(set) # key = streamNumer, value = a set which holds the inventory object hashes that we are aware of. This is used whenever we receive an inv message from a peer to check to see what items are new to us. We don't delete things out of it; instead, the singleCleaner thread clears and refills it every couple hours.
+        self._objects = {} # cache for existing objects, used for quick lookups if we have an object. This is used for example whenever we receive an inv message from a peer to check to see what items are new to us. We don't delete things out of it; instead, the singleCleaner thread clears and refills it.
         self.lock = RLock() # Guarantees that two receiveDataThreads don't receive and process the same message concurrently (probably sent by a malicious individual)
 
     def __contains__(self, hash):
         with self.lock:
-            if hash in self._inventory:
+            if hash in self._objects:
                 return True
-            return bool(sqlQuery('SELECT 1 FROM inventory WHERE hash=?', sqlite3.Binary(hash)))
+            rows = sqlQuery('SELECT streamnumber FROM inventory WHERE hash=?', sqlite3.Binary(hash))
+            if not rows:
+                return False
+            self._objects[hash] = rows[0][0]
+            return True
 
     def __getitem__(self, hash):
         with self.lock:
@@ -33,7 +37,7 @@ class SqliteInventory(InventoryStorage):
         with self.lock:
             value = InventoryItem(*value)
             self._inventory[hash] = value
-            self._streams[value.stream].add(hash)
+            self._objects[hash] = value.stream
 
     def __delitem__(self, hash):
         raise NotImplementedError
@@ -54,10 +58,6 @@ class SqliteInventory(InventoryStorage):
             values += (InventoryItem(*value) for value in sqlQuery('SELECT objecttype, streamnumber, payload, expirestime, tag FROM inventory WHERE objecttype=? AND tag=?', objectType, sqlite3.Binary(tag)))
             return values
 
-    def hashes_by_stream(self, stream):
-        with self.lock:
-            return self._streams[stream]
-
     def unexpired_hashes_by_stream(self, stream):
         with self.lock:
             t = int(time.time())
@@ -75,7 +75,7 @@ class SqliteInventory(InventoryStorage):
     def clean(self):
         with self.lock:
             sqlExecute('DELETE FROM inventory WHERE expirestime<?',int(time.time()) - (60 * 60 * 3))
-            self._streams.clear()
+            self._objects.clear()
             for objectHash, value in self._inventory.items():
-                self._streams[value.stream].add(objectHash)
+                self._objects[objectHash] = value.stream
 
diff --git a/src/storage/storage.py b/src/storage/storage.py
index 302c84a0..08c85708 100644
--- a/src/storage/storage.py
+++ b/src/storage/storage.py
@@ -33,9 +33,6 @@ class InventoryStorage(Storage, collections.MutableMapping):
     def by_type_and_tag(self, objectType, tag):
         raise NotImplementedError
 
-    def hashes_by_stream(self, stream):
-        raise NotImplementedError
-
     def unexpired_hashes_by_stream(self, stream):
         raise NotImplementedError