DANDI database migration procedure

[kabilar]

• Discuss strategies with Kitware team on the Django migrations. Since LINC is now dependent on the changes in DANDI, perhaps squash migrations should not occur.

[aaronkanzer]

Root of the problem is that linc-archive (and any other dandi-archive forks) will rely on Django DB migrations as a source-of-truth for their own database schemas.

We should limit this operation in the future so that downstream users do not find themselves with inconsistent migration history. The common resolution to this issue is manual invocation of Django commands and Python scripts. Manual alteration of Django migrations presents substantial risk so this is less than ideal.

See dandi#1778 (comment) for some context. I would politely disagree with the rationale of squashing migrations.

[aaronkanzer]

Noting for future reference --

In this most recent scenario, I had to backup the DB via heroku pg:backups, then reset the DB, then heroku pg:backups:restore <db-backup-id> DATABASE_URL --app linc-staging-terraform --confirm linc-staging-terraform

Process worked OK -- could not confirm though how bad downtime may have been....