#26019: Incorrect query generated when combining querysets refering to different
fields under the same alias.
-------------------------------------+-------------------------------------
Reporter: mssnlayam | Owner: nobody
Type: Bug | Status: new
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 charettes):
@shaib I agree but I assumed teaching the ORM to use `UNION` instead of
`UNION ALL` if combined queries use distinct could be done in an later
patch.
Given
{{{#!python
first_names = User.object.values(name='first_name')
last_names = User.object.values(name='last_name')
}}}
I would expect
{{{#!python
first_names.distinct() | last_names.distinct()
}}}
To result in
{{{#!sql
SELECT DISTINCT "auth_user"."first_name" AS "name" FROM "auth_user"
UNION ALL
SELECT DISTINCT "auth_user"."last_name" AS "name" FROM "auth_user"
}}}
And
{{{#!python
(first_names | last_names).distinct()
}}}
To result in
{{{#!sql
SELECT "auth_user"."first_name" AS "name" FROM "auth_user"
UNION
SELECT "auth_user"."last_name" AS "name" FROM "auth_user"
}}}
or the equivalent
{{{#!sql
SELECT DISTINCT "name" FROM (
SELECT "auth_user"."first_name" AS "name" FROM "auth_user"
UNION ALL
SELECT "auth_user"."last_name" AS "name" FROM "auth_user"
)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/26019#comment:6>
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