Fixed #36420 -- Used actual SQLite limits in last_executed_query() quoting.

django/db/backends/sqlite3/operations.py

@@ -1,5 +1,6 @@
 import datetime
 import decimal
+import sqlite3
 import uuid
 from functools import lru_cache
 from itertools import chain
@@ -143,16 +144,15 @@ class DatabaseOperations(BaseDatabaseOperations):
         """
         Only for last_executed_query! Don't use this to execute SQL queries!
         """
-        # This function is limited both by SQLITE_LIMIT_VARIABLE_NUMBER (the
-        # number of parameters, default = 999) and SQLITE_MAX_COLUMN (the
-        # number of return values, default = 2000). Since Python's sqlite3
-        # module doesn't expose the get_limit() C API, assume the default
-        # limits are in effect and split the work in batches if needed.
-        BATCH_SIZE = 999
-        if len(params) > BATCH_SIZE:
+        connection = self.connection.connection
+        variable_limit = self.connection.features.max_query_params
+        column_limit = connection.getlimit(sqlite3.SQLITE_LIMIT_COLUMN)
+        batch_size = min(variable_limit, column_limit)
+
+        if len(params) > batch_size:
             results = ()
-            for index in range(0, len(params), BATCH_SIZE):
-                chunk = params[index : index + BATCH_SIZE]
+            for index in range(0, len(params), batch_size):
+                chunk = params[index : index + batch_size]
                 results += self._quote_params_for_last_executed_query(chunk)
             return results
 

tests/backends/sqlite/tests.py

@@ -1,5 +1,6 @@
 import os
 import re
+import sqlite3
 import tempfile
 import threading
 import unittest
@@ -215,15 +216,28 @@ class LastExecutedQueryTest(TestCase):
         substituted = "SELECT '\"''\\'"
         self.assertEqual(connection.queries[-1]["sql"], substituted)
 
-    def test_large_number_of_parameters(self):
-        # If SQLITE_MAX_VARIABLE_NUMBER (default = 999) has been changed to be
-        # greater than SQLITE_MAX_COLUMN (default = 2000), last_executed_query
-        # can hit the SQLITE_MAX_COLUMN limit (#26063).
+    def test_parameter_count_exceeds_variable_or_column_limit(self):
+        sql = "SELECT MAX(%s)" % ", ".join(["%s"] * 1001)
+        params = list(range(1001))
+        for label, limit, current_limit in [
+            (
+                "variable",
+                sqlite3.SQLITE_LIMIT_VARIABLE_NUMBER,
+                connection.features.max_query_params,
+            ),
+            (
+                "column",
+                sqlite3.SQLITE_LIMIT_COLUMN,
+                connection.connection.getlimit(sqlite3.SQLITE_LIMIT_COLUMN),
+            ),
+        ]:
+            with self.subTest(limit=label):
+                connection.connection.setlimit(limit, 1000)
+                self.addCleanup(connection.connection.setlimit, limit, current_limit)
                 with connection.cursor() as cursor:
-            sql = "SELECT MAX(%s)" % ", ".join(["%s"] * 2001)
-            params = list(range(2001))
                     # This should not raise an exception.
                     cursor.db.ops.last_executed_query(cursor.cursor, sql, params)
+                connection.connection.setlimit(limit, current_limit)
 
 
 @unittest.skipUnless(connection.vendor == "sqlite", "SQLite tests")