#28600 closed New feature (fixed)
Add prefetch related support to RawQuerySet
Reported by: | Adnan Umer | Owned by: | Adnan Umer |
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Component: | Database layer (models, ORM) | Version: | dev |
Severity: | Normal | Keywords: | |
Cc: | Дилян Палаузов, Carlton Gibson | Triage Stage: | Ready for checkin |
Has patch: | yes | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description (last modified by )
When using custom raw SQL queries with Django ORM,
- There is no support to prefetch related models to increase performance
- Query results need to be cached manually
Change History (25)
comment:1 by , 7 years ago
Owner: | changed from | to
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Status: | new → assigned |
comment:2 by , 7 years ago
Has patch: | unset |
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Summary: | Prefetch Related Support in RawQuerySet → Add prefetch related support to RawQuerySet |
Triage Stage: | Unreviewed → Accepted |
comment:3 by , 7 years ago
Has patch: | set |
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Needs tests: | set |
Here is the link to PR that enabled this feature PR
follow-up: 6 comment:4 by , 7 years ago
Would you mind implementing the same for bulk_create() #28692?
comment:5 by , 7 years ago
Cc: | added |
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comment:6 by , 7 years ago
Replying to Дилян Палаузов:
Would you mind implementing the same for bulk_create() #28692?
Once someone accept the ticket, I'll post commit solution of that. BTW you can temporarily avoid that situation this way
models = ModelA.objects.bulk_create([ModelA(...), ModelA(...), ModelA(...)]) from django.db.models import prefetch_related_objects prefetch_related_objects(models, 'b') for m in models: print(m.b.description) # No more extra SELECT query here
comment:7 by , 7 years ago
Needs documentation: | set |
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Patch needs improvement: | set |
comment:8 by , 7 years ago
Description: | modified (diff) |
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Needs tests: | unset |
follow-up: 10 comment:9 by , 7 years ago
Unless __bool__
and __len__
support is required for prefetch_related
to work they should be added/tracked in another PR/ticket.
follow-up: 20 comment:10 by , 7 years ago
Replying to Simon Charette:
Unless
__bool__
and__len__
support is required forprefetch_related
to work they should be added/tracked in another PR/ticket.
Got that. Moving that to separate PR.
comment:11 by , 7 years ago
Description: | modified (diff) |
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comment:12 by , 7 years ago
Needs documentation: | unset |
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Patch needs improvement: | unset |
comment:13 by , 7 years ago
Owner: | removed |
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Status: | assigned → new |
comment:14 by , 7 years ago
Owner: | set to |
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Status: | new → assigned |
comment:15 by , 7 years ago
Patch needs improvement: | set |
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comment:16 by , 7 years ago
Patch needs improvement: | unset |
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comment:17 by , 6 years ago
Patch needs improvement: | set |
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comment:18 by , 6 years ago
Patch needs improvement: | unset |
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Did requested changes. Requesting to review the PR again.
comment:19 by , 6 years ago
Needs documentation: | set |
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Patch is looking good. Just needs some adjustments to the documentation changes.
follow-up: 21 comment:20 by , 6 years ago
Cc: | added |
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Replying to Adnan Umer:
Replying to Simon Charette:
Unless
__bool__
and__len__
support is required forprefetch_related
to work they should be added/tracked in another PR/ticket.
Got that. Moving that to separate PR.
Did that happen? (I can't see another PR by Adnan)
I ask because the warning in docs/db/sql.txt about this will also need updating:
__bool__()
and__len__()
are not defined inRawQuerySet
, and
thus allRawQuerySet
instances are considered
True
. The reason
these methods are not implemented inRawQuerySet
is that implementing
them without internal caching would be a performance drawback and adding
such caching would be backward incompatible.
comment:21 by , 6 years ago
Replying to Carlton Gibson:
Did that happen? (I can't see another PR by Adnan)
I havn't yet opened any new PR for that. I was just waiting on approval/merge of my existing ticket. Once that is done I'll create a new PR for that.
I ask because the warning in docs/db/sql.txt about this will also need updating:
Yes, I've created #29337 and assigned that to myself. Not sure should I open PR once this one got merged or before merge
comment:22 by , 6 years ago
Needs documentation: | unset |
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Unchecking "Needs Documentation" to have PR reviewed again after doing requested changes.
comment:23 by , 6 years ago
Triage Stage: | Accepted → Ready for checkin |
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Tentatively accepting, although I haven't looked into the history to understand if there's a design reason why it's not implemented. A post on django-users suggests that using
prefetch_related_objects()
(which has since been documented as a public API) works.I'm unchecking "Has patch" as I don't see a patch anywhere. If there's a patch somewhere, please provide a link.