diff --git a/minode/connection.py b/minode/connection.py
index fbd0306..80bceca 100644
--- a/minode/connection.py
+++ b/minode/connection.py
@@ -408,7 +408,7 @@ class ConnectionBase(threading.Thread):
 
     def _request_objects(self):
         if self.vectors_to_get and len(self.vectors_requested) < 100:
-            self.vectors_to_get.difference_update(shared.objects.keys())
+            self.vectors_to_get = shared.objects.select(self.vectors_to_get)
             if not self.wait_until:
                 nodes_count = (
                     len(shared.node_pool) + len(shared.unchecked_node_pool))
@@ -466,9 +466,7 @@ class Connection(ConnectionBase):
     def _process_msg_inv(self, m):
         inv = message.Inv.from_message(m)
         logging.debug('%s:%s -> %s', self.host_print, self.port, inv)
-        to_get = inv.vectors.copy()
-        to_get.difference_update(shared.objects.keys())
-        self.vectors_to_get.update(to_get)
+        self.vectors_to_get.update(shared.objects.select(inv.vectors))
         # Do not send objects they already have.
         self.vectors_to_send.difference_update(inv.vectors)
 
diff --git a/minode/sql.py b/minode/sql.py
index ba41fb3..ec84533 100644
--- a/minode/sql.py
+++ b/minode/sql.py
@@ -16,6 +16,7 @@ class Inventory():
     def __init__(self):
         self._lock = threading.Lock()
         self._deleted = 0
+        self._pending = set()
         self._db = sqlite3.connect(
             os.path.join(shared.data_directory, 'objects.dat'),
             check_same_thread=False
@@ -56,6 +57,10 @@ class Inventory():
         return cur
 
     def cleanup(self):
+        if len(self._pending) > 100:
+            logging.warning(
+                'Not cleaning up, %s objects pending', len(self._pending))
+            return
         with self._lock:
             cur = self._db.execute(
                 'DELETE FROM objects WHERE expires < ?',
@@ -72,7 +77,9 @@ class Inventory():
                     (int(time.time()),))
                 self._db.commit()
                 self._deleted = 0
-        logging.info('Deleted %s expired objects', cur.rowcount)
+        logging.info(
+            'Deleted %s expired objects, %s pending',
+            cur.rowcount, len(self._pending))
 
     def filter(self, stream=None, object_type=None, tag=None):
         clauses = []
@@ -89,6 +96,20 @@ class Inventory():
             'SELECT * FROM objects WHERE ' + ' AND '.join(clauses), params)
         return self.__objects(cur)
 
+    def select(self, vectors):
+        chunk_size = 999
+        keys = tuple(vectors)
+        with self._lock:
+            for i in range(0, len(vectors), chunk_size):
+                chunk = keys[i:i+chunk_size]
+                cur = self._db.execute(
+                    'SELECT vector FROM objects WHERE vector IN ({})'.format(
+                        ','.join('?' * len(chunk))), chunk)
+                for v, in cur:
+                    vectors.remove(v)
+        self._pending.update(vectors)
+        return vectors
+
     def vectors_to_send(self, stream=None):
         cur = self._db.execute(
             'SELECT vector FROM objects WHERE expires > ? AND stream = ?'
@@ -154,6 +175,7 @@ class Inventory():
                 return
             self._db.commit()
             self.rowid = cur.lastrowid
+        self._pending.discard(vector)
 
     def __len__(self):
         cur = self._db.execute('SELECT count(*) FROM objects')