Avoid unnecessary queries in Cable.from_db #3745

New Issue

adam · 2025-12-29T18:30:53+01:00

adam commented

2025-12-29 18:30:53 +01:00

Originally created by @steffann on GitHub (Jun 4, 2020).

Originally assigned to: @steffann on GitHub.

Proposed Changes

Change the code in https://github.com/netbox-community/netbox/blob/develop/netbox/dcim/models/init.py#L2118-L2121 where a copy is made of the termination points. I suggest to change it to:

instance._orig_termination_a_type_id = instance.termination_a_type_id
instance._orig_termination_a_id = instance.termination_a_id
instance._orig_termination_b_type_id = instance.termination_b_type_id
instance._orig_termination_b_id = instance.termination_b_id

And change the corresponding usage to:

if (
    self.termination_a_type_id != self._orig_termination_a_type_id or
    self.termination_a_id != self._orig_termination_a_id
):
    raise ValidationError({
        'termination_a': err_msg
    })
if (
    self.termination_b_type_id != self._orig_termination_b_type_id or
    self.termination_b_id != self._orig_termination_b_id
):
    raise ValidationError({
        'termination_b': err_msg
    })

Justification

Reading the …_type properties triggers database queries to retrieve a ContentType object, which is later only used in a comparison. Storing the …_type_id is sufficient for that and avoids the queries.

Originally created by @steffann on GitHub (Jun 4, 2020). Originally assigned to: @steffann on GitHub. ### Proposed Changes Change the code in https://github.com/netbox-community/netbox/blob/develop/netbox/dcim/models/__init__.py#L2118-L2121 where a copy is made of the termination points. I suggest to change it to: ``` instance._orig_termination_a_type_id = instance.termination_a_type_id instance._orig_termination_a_id = instance.termination_a_id instance._orig_termination_b_type_id = instance.termination_b_type_id instance._orig_termination_b_id = instance.termination_b_id ``` And change the corresponding usage to: ``` if ( self.termination_a_type_id != self._orig_termination_a_type_id or self.termination_a_id != self._orig_termination_a_id ): raise ValidationError({ 'termination_a': err_msg }) if ( self.termination_b_type_id != self._orig_termination_b_type_id or self.termination_b_id != self._orig_termination_b_id ): raise ValidationError({ 'termination_b': err_msg }) ``` ### Justification Reading the `…_type` properties triggers database queries to retrieve a `ContentType` object, which is later only used in a comparison. Storing the `…_type_id` is sufficient for that and avoids the queries.

adam added the status: accepted type: housekeeping labels 2025-12-29 18:30:53 +01:00

adam closed this issue

2025-12-29 18:30:54 +01:00

adam commented

2025-12-29 18:30:54 +01:00

@steffann commented on GitHub (Jun 4, 2020):

I noticed this behaviour when looking at the debug toolbar:

I tested with prefetch_related, but that doesn't affect the behaviour. It fetches the cables in one query, which is then followed by all the queries for the content types, one by one.

@steffann commented on GitHub (Jun 4, 2020): I noticed this behaviour when looking at the debug toolbar: <img width="1191" alt="Schermafbeelding 2020-06-04 om 16 21 47" src="https://user-images.githubusercontent.com/509689/83769357-064dad00-a680-11ea-9746-4bb29cb5c373.png"> I tested with `prefetch_related`, but that doesn't affect the behaviour. It fetches the cables in one query, which is then followed by all the queries for the content types, one by one.