Refs #30897 -- Added support for TREE format to Queryset.explain() on MySQL 8.0.16+.

django/db/backends/mysql/features.py

@@ -48,8 +48,6 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         END;
     """
     db_functions_convert_bytes_to_str = True
-    # Alias MySQL's TRADITIONAL to TEXT for consistency with other backends.
-    supported_explain_formats = {'JSON', 'TEXT', 'TRADITIONAL'}
     # Neither MySQL nor MariaDB support partial indexes.
     supports_partial_indexes = False
 
@@ -119,6 +117,15 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         # EXTENDED is deprecated (and not required) in MySQL 5.7.
         return not self.connection.mysql_is_mariadb and self.connection.mysql_version < (5, 7)
 
+    @cached_property
+    def supported_explain_formats(self):
+        # Alias MySQL's TRADITIONAL to TEXT for consistency with other
+        # backends.
+        formats = {'JSON', 'TEXT', 'TRADITIONAL'}
+        if not self.connection.mysql_is_mariadb and self.connection.mysql_version >= (8, 0, 16):
+            formats.add('TREE')
+        return formats
+
     @cached_property
     def supports_transactions(self):
         """

django/db/backends/mysql/operations.py

@@ -296,6 +296,9 @@ class DatabaseOperations(BaseDatabaseOperations):
         # Alias MySQL's TRADITIONAL to TEXT for consistency with other backends.
         if format and format.upper() == 'TEXT':
             format = 'TRADITIONAL'
+        elif not format and 'TREE' in self.connection.features.supported_explain_formats:
+            # Use TREE by default (if supported) as it's more informative.
+            format = 'TREE'
         prefix = super().explain_query_prefix(format, **options)
         if format:
             prefix += ' FORMAT=%s' % format