Improve efficiency of MongoDB reader (#12664)

llama-index-integrations/readers/llama-index-readers-mongodb/llama_index/readers/mongodb/base.py

@@ -78,7 +78,11 @@ class SimpleMongoReader(BaseReader):
 
         """
         db = self.client[db_name]
-        cursor = db[collection_name].find(filter=query_dict or {}, limit=max_docs)
+        cursor = db[collection_name].find(
+            filter=query_dict or {},
+            limit=max_docs,
+            projection={name: 1 for name in field_names + (metadata_names or [])},
+        )
 
         for item in cursor:
             try:

llama-index-integrations/readers/llama-index-readers-mongodb/pyproject.toml

@@ -28,7 +28,7 @@ license = "MIT"
 maintainers = ["jerryjliu"]
 name = "llama-index-readers-mongodb"
 readme = "README.md"
-version = "0.1.3"
+version = "0.1.4"
 
 [tool.poetry.dependencies]
 python = ">=3.8.1,<4.0"