The Missing Piece in Indexing

[Behzad]

Hey all!

I noticed a while ago that we can set indexes in the models Meta as described here. But I can't find any commands on the Queryset which helps us use the declared indexes, the equivalent of `USE INDEX` in the DB.

Is this planned to be developed?

Best

Behzad

[Adam Johnson]

Hi Behzad

Your database will automatically use the appropriate indexes for given queries, thanks to its optimizer. See https://en.m.wikipedia.org/wiki/Query_optimization and DB specific docs such as: https://www.postgresql.org/docs/9.0/planner-optimizer.html , https://dev.mysql.com/doc/internals/en/optimizer.html .

USE INDEX is only for forcing usage of particular indexes if you are *sure* that you know better than your optimizer. You don't need it in 99% of cases, it's a bit of a sledgehammer, and prone to bitrot into bad performance if your tables change. However if you're sure you want to do this, for MySQL/MariaDB, my library Django-MySQL adds a QuerySet extension for it: https://django-mysql.readthedocs.io/en/latest/queryset_extensions.html#django_mysql.models.use_index . I've actually never ended up needing it myself.

Thanks,

Adam

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Adam