restored default client-side chunking behavior

Author: Jibola

django_mongodb_backend/compiler.py

@@ -11,7 +11,7 @@
 from django.db.models.functions.math import Power
 from django.db.models.lookups import IsNull
 from django.db.models.sql import compiler
-from django.db.models.sql.constants import MULTI, SINGLE
+from django.db.models.sql.constants import GET_ITERATOR_CHUNK_SIZE, MULTI, SINGLE
 from django.db.models.sql.datastructures import BaseTable
 from django.utils.functional import cached_property
 from pymongo import ASCENDING, DESCENDING
@@ -235,7 +235,9 @@ def pre_sql_setup(self, with_col_aliases=False):
         self.order_by_objs = [expr.replace_expressions(all_replacements) for expr, _ in order_by]
         return extra_select, order_by, group_by
 
-    def execute_sql(self, result_type=MULTI, chunked_fetch=False, chunk_size=None):
+    def execute_sql(
+        self, result_type=MULTI, chunked_fetch=False, chunk_size=GET_ITERATOR_CHUNK_SIZE
+    ):
         self.pre_sql_setup()
         try:
             query = self.build_query(
@@ -315,16 +317,15 @@ def _make_result(self, entity, columns):
             result.append(obj.get(name))
         return result
 
-    def cursor_iter(self, cursor, _, columns):
-        """
-        Yield chunks of results from cursor.
-        Ignore any chunk_size/batch_size overrides and abide by MongoDB's
-        default chunking behavior. This maximizes performance on document
-        retrieval.
-        Read more here: https://www.mongodb.com/docs/manual/core/cursors/#cursor-batches
-        """
+    def cursor_iter(self, cursor, chunk_size, columns):
+        """Yield chunks of results from cursor."""
+        chunk = []
         for row in cursor:
-            yield [self._make_result(row, columns)]
+            chunk.append(self._make_result(row, columns))
+            if len(chunk) == chunk_size:
+                yield chunk
+                chunk = []
+        yield chunk
 
     def check_query(self):
         """Check if the current query is supported by the database."""

docs/source/releases/5.1.x.rst

@@ -15,10 +15,8 @@ Bug fixes
   the ``base_field`` uses a database converter.
 - Fixed ``RecursionError`` when using ``Trunc`` database functions on non-MongoDB
   databases.
-- Removed user configurable request chunking. Allowing MongoDB to
+- Removed user configurable server-side request chunking. Allowing MongoDB to
   handle chunking automatically improves performance and reduces complexity.
-  As a result, :meth:`QuerySet.iterator() <django.db.models.query.QuerySet.iterator>`
-  ignores the ``chunk_size`` parameter.
 
 
 5.1.0 beta 3

docs/source/releases/5.2.x.rst

@@ -25,10 +25,8 @@ Bug fixes
   databases.
 - :meth:`QuerySet.explain() <django.db.models.query.QuerySet.explain>` now
   :ref:`returns a string that can be parsed as JSON <queryset-explain>`.
-- Removed user configurable request chunking. Allowing MongoDB to
+- Removed user configurable server-side request chunking. Allowing MongoDB to
   handle chunking automatically improves performance and reduces complexity.
-  As a result, :meth:`QuerySet.iterator() <django.db.models.query.QuerySet.iterator>`
-  ignores the ``chunk_size`` parameter.
 
 
 5.2.0 beta 1