Later migrations added fields to the EE DB which were used by factories which were used in these specs.

And in CE on MySQL, a single appearance row is enforced.

The migration and migration specs should not depend on the codebase staying the same.

In particular, the Omnibus uploads directory is generally a symlink.

To fix for MySQL.

`updated_at` is now unnecessary and `created_at` is less useful due to removing the tracked field.

It makes a debugging slightly easier, but is not necessary, and is a waste of resources.

* Hopefully fixes spec failures in which the table doesn’t exist
* Decouples the background migration from the post-deploy migration, e.g. we could easily run it again even though the table is dropped when finished.

Since `calculate_checksum` depends on `Uploader` classes which are not defined in this background migration and may change at any time.

This will prevent our other migration for adding old files to the uploads table from breaking.

I believe the field only needs to fit 519 at the moment but I’m rounding up to be a little safer.

See the migration spec for more detail on the magic number 519.

So the path on source installs cannot be too long for our column.

And fix the column length test since Route.path is limited to 255 chars, it doesn’t matter how many nested groups there are.

Because it is a temporary table meant only to facilitate a migration of data. It is referenced only by the post-deploy migration and 2 related background migrations.

It should be dropped when the data migration is finished.