Fixed #27060: Extended inspectdb so indexes are added to Meta.indexes.

[drewbrew]

When inspecting tables, the process creates a constraints dict
that identifies indexes. If we have any such indexes, let's add
them to Meta.indexes using the base Index class.

At this point, it does not support identifying the index type and
substituting in the proper index class, and I don't believe we have
the information at this time to select the right class anyway.

Ref: https://code.djangoproject.com/ticket/27060

[drewbrew]

Fix for docs test is at #12698.

[felixxm]

@drewbrew Thanks for this patch 👍 Please take a look at the previous attempt #7083 and all comments in the ticket. This patch should take into account indexes' types and various parameters (e.g. fillfactor).

[drewbrew]

Thanks for that pointer, @felixxm.

So far, I've:

• added in the type check (at least to the level of marking a comment if it's not the default type)
• skipped single-column rtree indexes (and making a note of it in case the assumption that it's a default spatial index is wrong)
• added support for index ordering (if available)

(Tests are still wonky, I know)

I'm a little confused by the postgres-specific options. My initial thought is that I'm going to have to do some sort of mapping from Index subclassses' type to that class (in the postgres introspection module) and convert the the options as returned from the db into kwargs accordingly. Does that sound like a reasonable and maintainable approach?

[nessita]

Hello @drewbrew, I'm doing some PR cleanup. Do you have time to keep working on this? If yes, would you consider rebasing onto main, resolve conflicts, and flag this PR for review? Thank you!

[drewbrew]

Thanks for the prod, @nessita (and congrats on being the new fellow!). I've rebased it (correctly I hope... a lot changes in 3 years!), but how do I flag for review? Just convert it to a draft and back?

[nessita]

Thank you @drewbrew. Could you please revert the changes you made to AUTHORS (other than adding your name to it)?

[nessita]

Also, @drewbrew, would you care commenting in the ticket, specifically replying to the last comment made by @David-Wobrock?