How to get unique data for each column from the database in one query (Django ORM)?

I need to get UNIQUE data from EACH column I have a list of fields:

MY_FIELDS = ['id', 'created', 'And_more_28']

My HORRIBLY INEFFECTIVE code that produces the correct result

qs = Sheets.objects.all()
v = []
v += [list(qs.values(v).distinct()) for v in MY_FIELDS]

I get what I need.... But at what cost? (28 requests is painful) Tell me how to make one query out of this....

This is how it produces non-unique data for EACH column (tried it)

qs = Sheets.objects.all().values(*MY_FIELDS).distinct()

Solution

Your second approach does produce unique values, but these are unique combinations. So if there are 10 fields with each 5 values, that already can result in at most 5¹⁰ results, so it scales dramatically.

But the good news is, we can solve this, by aggregating all columns into distinct lists. Indeed, with ArrayAgg ^[Django-doc]:

MY_FIELDS = ['id', 'created', 'And_more_28']

from django.contrib.postgres.aggregates import ArrayAgg

qs = Sheets.objects.aggregate(
    **{'values_{f}': ArrayAgg('f', distinct=True) for f in MY_FIELDS}
)
v = [qs[f'values_{f}'] for f in MY_FIELDS]

This will produce lists of distinct values for each column, and all in one single query.