diff --git a/src/calibre/library/database.py b/src/calibre/library/database.py
index 86316c738e..fc29df5f02 100644
--- a/src/calibre/library/database.py
+++ b/src/calibre/library/database.py
@@ -1086,9 +1086,12 @@ ALTER TABLE books ADD COLUMN isbn TEXT DEFAULT "" COLLATE NOCASE;
         return None
 
     def has_conversion_options(self, ids, format='PIPE'):
+        ids = tuple(ids)
+        if len(ids) > 50000:
+            return True
         return self.conn.get('''
             SELECT data FROM conversion_options WHERE book IN %r AND
-        format=? LIMIT 1'''%(tuple(ids),), (format,), all=False) is not None
+        format=? LIMIT 1'''%(ids,), (format,), all=False) is not None
 
     def delete_conversion_options(self, id, format, commit=True):
         self.conn.execute('DELETE FROM conversion_options WHERE book=? AND format=?',