[Django] #16043: Specialization cache should be filled/shared with parent object cache (multitable inheritance)
Django
(multitable inheritance)
----------------------------+----------------------------------------------
Reporter: zimnyx | Owner: nobody
Type: | Status: new
Cleanup/optimization | Component: Database layer (models, ORM)
Milestone: | Severity: Normal
Version: SVN | Triage Stage: Unreviewed
Keywords: | Easy pickings: 0
Has patch: 0 |
----------------------------+----------------------------------------------
Here is some multi-table inheritance example:
{{{
class Owner(models.Model):
nick = models.CharField(max_length=100)
class Car(models.Model):
owner = models.ForeignKey(Owner)
some_id = models.CharField(max_length=100)
class MiniMorris(Car):
mini_type = models.CharField(max_length=1)
}}}
{{{
- model: auto.Owner
pk: 1
fields:
nick: Homer
- model: auto.Car
pk: 1
fields:
owner: 1
some_id: 'minii A'
- model: auto.MiniMorris
pk: 1
fields:
mini_type: 'e'
}}}
{{{
>>> c = Car.objects.select_related('owner').get(pk=1)
>>> # SELECT "auto_car"."id", "auto_car"."owner_id", "auto_car"."some_id",
"auto_owner"."id", "auto_owner"."nick" FROM "auto_car" INNER JOIN
"auto_owner" ON ("auto_car"."owner_id" = "auto_owner"."id") WHERE
"auto_car"."id" = 1
>>> c.owner
<Owner: Owner object>
>>> # No SQL, cache hit.
>>> m = c.minimorris
>>> # SELECT "auto_car"."id", "auto_car"."owner_id", "auto_car"."some_id",
"auto_minimorris"."car_ptr_id", "auto_minimorris"."mini_type" FROM
"auto_minimorris" INNER JOIN "auto_car" ON ("auto_minimorris"."car_ptr_id"
= "auto_car"."id") WHERE "auto_minimorris"."car_ptr_id" = 1
>>> # SQL is fine, we need to obtain this specialization
>>> m.owner
<Owner: Owner object>
>>> # SELECT "auto_owner"."id", "auto_owner"."nick" FROM "auto_owner"
WHERE "auto_owner"."id" = 1
>>> # Redundant SQL. This could be obtained from cache.
}}}
SQL issued by "m.owner" is redundant as owner is already cached in parent
object.
--
Ticket URL: <http://code.djangoproject.com/ticket/16043>
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Django
(multitable inheritance)
Type: | Status: new
Cleanup/optimization | Component: Database layer
Version: SVN | Severity: Normal
Resolution: | Keywords:
Triage Stage: Accepted | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
-------------------------------------+-------------------------------------
Changes (by aaugustin):
* needs_better_patch: => 0
* stage: Unreviewed => Accepted
* needs_tests: => 0
* needs_docs: => 0
Comment:
This looks a lot like #15250, but it's not exactly the same bug. At least,
the patch currently available on #15250 does not fix this issue.
I'm attaching a test case in the form of a patch.
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:1>
Django
(multitable inheritance)
Reporter: zimnyx | Owner: nobody
Type: | Status: new
Component: Database layer | Resolution:
(models, ORM) | Triage Stage: Accepted
Severity: Normal | Needs documentation: 0
Keywords: | Patch needs improvement: 0
Has patch: 0 | UI/UX: 0
Needs tests: 0 |
Easy pickings: 0 |
-------------------------------------+-------------------------------------
Comment (by aaugustin):
The issue still exists. However, it can be reproduced without
select_related. The problem is really in model inheritance. So the test
case I wrote two years ago is inappropriate.
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:3>
Django
(multitable inheritance)
Reporter: zimnyx | Owner: nobody
Type: | Status: new
Cleanup/optimization |
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
-------------------------------------+-------------------------------------
Comment (by timgraham):
#25173 seems to be a duplicate and also has a test.
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:4>
Django
(multitable inheritance)
Reporter: zimnyx | Owner: czpython
Type: | Status: assigned
Cleanup/optimization |
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
* owner: nobody => czpython
* status: new => assigned
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:5>
Django
(multitable inheritance)
Reporter: zimnyx | Owner: czpython
Type: | Status: assigned
Cleanup/optimization |
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by czpython):
* has_patch: 0 => 1
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:6>
Django
(multitable inheritance)
Reporter: zimnyx | Owner: czpython
Type: | Status: assigned
Cleanup/optimization |
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by phildini):
I believe the PR czpython made for this ticket is
https://github.com/django/django/pull/6721.
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:7>
Django
(multitable inheritance)
Reporter: zimnyx | Owner: czpython
Type: | Status: assigned
Cleanup/optimization |
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
* has_patch: 1 => 0
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:8>
Django
(multitable inheritance)
Reporter: zimnyx | Owner: czpython
Type: | Status: assigned
Cleanup/optimization |
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by czpython):
Removed the has patch set flag as PR 6721 is only the base for this.
The fix will be in a separate PR.
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:9>
Django
(multitable inheritance)
Reporter: Piotr Czachur | Owner: Paulo
Type: | Status: assigned
Cleanup/optimization |
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Tim Graham <timograham@…>):
In [changeset:"bfb746f983aa741afa3709794e70f1e0ab6040b5" bfb746f9]:
{{{
#!CommitTicketReference repository=""
revision="bfb746f983aa741afa3709794e70f1e0ab6040b5"
Refs #16043 -- Refactored internal fields value cache.
* Removed all hardcoded logic for _{fieldname}_cache.
* Added an internal API for interacting with the field values cache.
Thanks carljm and MarkusH for support.
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:10>
Django
(multitable inheritance)
Reporter: Piotr Czachur | Owner: Paulo
Cleanup/optimization |
Component: Database layer | Version: master
(models, ORM) |
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
* status: assigned => closed
* resolution: => fixed
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:11>
Django
(multitable inheritance)
Reporter: Piotr Czachur | Owner: Paulo
Cleanup/optimization |
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
* status: closed => new
* resolution: fixed =>
Comment:
I think a regression test should be added before closing this ticket.
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:12>
Django
(multitable inheritance)
Reporter: Piotr Czachur | Owner: Paulo
Cleanup/optimization |
Component: Database layer | Version: master
(models, ORM) |
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Tim Graham):
* status: new => closed
* resolution: => fixed
Comment:
After investigation, I found that this was fixed by
78c5e7b90eee10067d39a8ba6588e6b53ba00d82 which did add an appropriate
test.
--
Ticket URL: <https://code.djangoproject.com/ticket/16043#comment:13>