I did a similar thing (but only tested in postgres) a while back, using Q's / filter clause to generate the where clause.
Perhaps with our powers combined we're close to a generalised implementation? https://github.com/ashleywaite/django-more/blob/master/django_more/indexes.py On Saturday, October 7, 2017 at 7:56:00 PM UTC+11, Mattias Linnap wrote: > > Hi django-developers, > > I have written a package that implements PostgreSQL and SQLite partial > indexes on top of the new class-based indexes: > https://github.com/mattiaslinnap/django-partial-index > The most common use case is partial unique constraints, but I have a few > projects where non-unique partial indexes have turned out useful as well. > > I have a few questions on how to continue with this: > > 1. Right now the "where condition" expression is provided as a string, and > has to be different for PostgreSQL and SQLite in some common cases (for > example boolean literals). Is there a good abstraction for SQL expressions > somewhere in Django internals that I could use instead, something similar > to Q-expressions perhaps? In particular, to add validate_unique() support > to ModelForms, I would need to be able to extract all fields that are > mentioned in the where condition. > 2. I've seen mentions of a "check constraints" support being in > development (https://github.com/django/django/pull/7615). Will that > include partial unique constraints, or is just for the per-column checks? > 3. If separate, then it would be nice to one day get partial indexes > merged into the contrib.postgres package. Do you have any suggestions on > what needs to happen before that - more test coverage, more contributors, > more users, or similar? > > Best, > > Mattias > -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To post to this group, send email to django-developers@googlegroups.com. Visit this group at https://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/84f4431a-cdab-43c7-b96b-de4d2eb9805b%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
