Increase max backup size

[scd31]

Changes backup size from integer to bigint. This solves #12572

[Gargron]

What's going on here?

[scd31]

Seems that CURRENT_TIMESTAMP was added to Rails 5. I'm not sure why it decided to change in this PR(and I can change it back if needed). This seems like the more rails-y way to do it, as it is database-agnostic.

[Gargron]

Yes, I'd like to minimize the changes as much as possible. We don't need to be database-agnostic anyway because we use postgres-specific query features.

[scd31]

This should be fixed now

[Gargron]

This is okay but shouldn't have been there in the first place...

[zunda]

ActiveRecord complains about this migration. Might there be a workaround?

Migrating to IncreaseBackupSize (20191212003415)
== 20191212003415 IncreaseBackupSize: migrating ===============================
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:

=== Dangerous operation detected #strong_migrations ===

Changing the type of an existing column requires the entire
table and indexes to be rewritten. A safer approach is to:

1. Create a new column
2. Write to both columns
3. Backfill data from the old column to the new column
4. Move reads from the old column to the new column
5. Stop writing to the old column
6. Drop the old column

/app/db/migrate/20191212003415_increase_backup_size.rb:3:in `up'
  :

[scd31]

@zunda Well that sucks. I don't have time to fix that(Exam season is right now for me) but someone else should submit a PR to fix that. Otherwise I will have a PR up in a few days.

[noellabo]

Since the number of data in the backups table is usually very small and the target field is not indexed, operations that change the type of this field seem to be safe in practice.

Display the actual number of records and make sure it is small enough.

bin/rails r 'puts Backup.count'

If it looks okay, run migration with SAFETY_ASSURED=1.

SAFETY_ASSURED=1 RAILS_ENV=production bundle exec rails db:migrate

You can also change the migration code.

safety_assured { change_column :backups, :dump_file_size, :bigint }

[Gargron]

Since the schema version was updated in the PR, I assumed db:migrate has been run successfully. It's strange that this warning didn't come up. In practice I think that this table is so small it's okay to update the column live.

There is I believe also a migration helper to do this the safe way.

[scd31]

@Gargron I ran db:migrate, however my database was a clean slate(I had only just installed mastodon for development).
I agree that safety_assured { change_column :backups, :dump_file_size, :bigint } is the way to go.