[FIX] survey*: add missing index FKs for performance

1) `survey_user_input.slide_partner_id`: this is a sparse column (so using
`btree_not_null` means a very small footprint). But it makes a ton of
difference when trying to delete a slide.slide.partner entry.
e.g. on a db with 500k survey inputs, the deletion of 1000
`slide.slide.partner` records goes from 40s to 100ms (400x speedup)

2) `survey_user_input_line.survey_id`: this is the inverse field of the
`survey_user_input.user_input_line_ids` O2M field, so the index is
always useful to retrieve the O2M lines. It will also marginally help
for cascading the deletion of any `survey_user_input` record from
case 1).

closes odoo/odoo#116875

X-original-commit: 2dc929cd530ba4fd80c17f91af2bfad02a819dd6
Signed-off-by: Olivier Dony (odo) <odo@odoo.com>

addons/survey/models/survey_user_input.py

@@ -614,7 +614,7 @@ class SurveyUserInputLine(models.Model):
     _order = 'question_sequence, id'
 
     # survey data
-    user_input_id = fields.Many2one('survey.user_input', string='User Input', ondelete='cascade', required=True)
+    user_input_id = fields.Many2one('survey.user_input', string='User Input', ondelete='cascade', required=True, index=True)
     survey_id = fields.Many2one(related='user_input_id.survey_id', string='Survey', store=True, readonly=False)
     question_id = fields.Many2one('survey.question', string='Question', ondelete='cascade', required=True)
     page_id = fields.Many2one(related='question_id.page_id', string="Section", readonly=False)

addons/website_slides_survey/models/survey_user.py

@@ -11,7 +11,8 @@ class SurveyUserInput(models.Model):
     slide_id = fields.Many2one('slide.slide', 'Related course slide',
         help="The related course slide when there is no membership information")
     slide_partner_id = fields.Many2one('slide.slide.partner', 'Subscriber information',
-        help="Slide membership information for the logged in user")
+        help="Slide membership information for the logged in user",
+        index='btree_not_null') # index useful for deletions in comodel
 
     @api.model_create_multi
     def create(self, vals_list):