PendingModelChangesWarning when migrating from .NET 8 to .NET 9 with multitenancy per schema

[dziedrius]

There are several issues reported related to PendingModelChangesWarning, but our case is quite unique, hence I've decided to open separate issue.
I did quite isolated repro: https://github.com/dziedrius/migration-efcore-9-issue (it is in .NET 8 currently, so that it would be possible to see how behavior changes after migrating to .NET 9)

What I was able to figure out:
So as long as EF Core does not support multitenancy per schema (kind of sad, as in my opinion that is one of the clearest way to do multitenancy), we did it ourselves, it needed custom code, but kind of manageable (strongly influenced by https://github.com/Oriflame/EFCoreMultitenantSample).

The problem is, that schema is applied to migration operations just during runtime, meaning that when migrator is checking diff for source/target models, it sees different schema and hence throws the exception, seems that this check was introduced in .NET 9.

I could not figure out how I could get better control over this, so used the only workaround I knew - disabled warning, and not sure if that is a good way to approach - as I'm loosing ability to get a warning when real model mismatches will appear.

Include provider and version information

EF Core version:
Database provider: (e.g. Npgsql.EntityFrameworkCore.PostgreSQL)
Target framework: (e.g. .NET 9.0)

[cincuranet]

Dupe of #35158.

[AndriySvyryd]

Disabling the warning is the correct approach in this case.

[roji]

Note: we've just published #35285 which provides more background and explanations around the new PendingModelChangesWarning; anyone still having trouble should go read that - hopefully it should help.