[Django]-Create composite index from a Django model

by

37👍

✅

Starting from django-1.5 you can make compound index using index_together meta option:
https://docs.djangoproject.com/en/dev/ref/models/options/#index-together

Note (2023/01/30) index_together is deprecated since django-4.2. Instead, use much more powerful indexes meta option. With it you can create not only compound indexes, but also other types of indexes, e.g. function-based indexes, partial (conditional) indexes, covering indexes:
https://docs.djangoproject.com/en/dev/ref/models/options/#django.db.models.Options.indexes

So, in your example index declaration would like this

from django.db import models

class PopulationData(models.Model):
    slot = models.IntegerField()
    sample = models.IntegerField()
    value = models.FloatField()

    class Meta:
        indexes = [
            models.Index("slot", "sample", name="population_slot_sample_idx")
        ]
👤Eugene Prikazchikov

8👍

Starting from Django-1.11 use Meta.indexes option https://docs.djangoproject.com/en/1.11/ref/models/indexes/:

from django.db import models

class PopulationData(models.Model):
    slot = models.IntegerField(db_index=True)
    sample = models.IntegerField()
    value = models.FloatField()

    class Meta:
        unique_together = (('slot', 'sample'),)
        indexes = [
            models.Index(fields=['slot', 'sample']),
        ]
👤Artem Likhvar

5👍

Since a unique constraint also creates an index, it would be counterproductive to create both.

for example, from the postgres docs:

There’s no need to manually create indexes on unique columns; doing so would just duplicate the automatically-created index.

Credit to Mark Byers for the doc link

If for some reason you still want to create a multi-column index, you can do so via index_together:

class PopulationData(models.Model):
    ...

    class Meta:
        index_together = [['slot', 'sample']]
👤Lord Elrond

2👍

I think that’s not currently implemented in the django ORM.

If you use a migration tool (like south) that might be a good place to add that sql statement or if you preffer to avoid raw sql you could use sqlalchemy (core) but this case sounds simple enough to just go with sql.

👤gonz

2👍

Note: index_together may be deprecated in the future:
https://docs.djangoproject.com/en/dev/ref/models/options/#index-together

Use indexes in the Meta class instead:

from django.db import models

class Customer(models.Model):
    first_name = models.CharField(max_length=100)
    last_name = models.CharField(max_length=100)

    class Meta:
        indexes = [
            models.Index(fields=['last_name', 'first_name']),
            models.Index(fields=['first_name'], name='first_name_idx'),
        ]
👤Boketto

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