#34078: Should the Postgres range_merge aggregate be added to postgres.contrib?
-------------------------------------+-------------------------------------
Reporter: Jack | Owner: (none)
Linke |
Type: New | Status: new
feature |
Component: | Version: 4.1
contrib.postgres | Keywords: postgres range
Severity: Normal | range_merge aggregation aggregate
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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Most of the Postgres range functions have been exposed for querying in
django, but not the {{{range_merge}}} Aggregate function.
As background, {{{range_merge}}} "Computes the smallest range that
includes ... the given ranges".
The existing Postgres functions exposed for queries in django:
https://docs.djangoproject.com/en/4.1/ref/contrib/postgres/fields
/#querying-using-the-bounds
The full list of Posgres range functions (note that range_merge is the
only one not represented in django): https://www.postgresql.org/docs/14
/functions-range.html#RANGE-FUNCTIONS-TABLE
----
To make use of this aggregation in my own project, I created a django
package that runs a migration to CREATE (or DROP) the aggregate function
in the database (https://pypi.org/project/django-range-merge/).
{{{
operations = [
migrations.RunSQL(
sql=[("CREATE OR REPLACE AGGREGATE
range_merge(anyrange)(sfunc=range_merge, stype=anyrange);")],
reverse_sql=[("DROP AGGREGATE IF EXISTS range_merge(anyrange);")],
)
]
}}}
Then, given the model:
{{{
class Event(models.Model):
name = models.CharField(max_length=30)
potential_visitors = models.IntegerRangeField()
}}}
And a few model instances:
{{{
{"id" : 1, "name" : "Birthday", "potential_visitors" : "[2, 3)"}
{"id" : 2, "name" : "Bake Sale", "potential_visitors" : "[30, 50)"}
{"id" : 3, "name" : "Band Camp", "potential_visitors" : "[22, 28)"}
{"id" : 4, "name" : "Cooking Show", "potential_visitors" : "[7, 20)"}
{"id" : 5, "name" : "Pajama Day", "potential_visitors" : "[15, 30)"}
}}}
Executing the query:
{{{
Event.objects.all().aggregate(
output=Aggregate(F("potential_visitors"), function="range_merge")
)
}}}
Returns:
{{{{'output': NumericRange(2, 50, '[)')}}}}
----
It looks like RunSQL is not used anywhere in django's codebase, except in
tests, so I am not sure if adding this to the contrib.postgres codebase
would be welcomed.
Should this be added to django, or should it remain as a package separate
from django itself?
--
Ticket URL: <https://code.djangoproject.com/ticket/34078>
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