migrations in ftd

[amitu]

Update

The previous design allows migration in any file, which has to be visited before migration is applied, or it requires us to watch for on save event and apply the migration. The on save event is unreliable as we may be using fastn with files directly on filesystem etc (where on save may not be relied upon).

So we will store migrations in FASTN.ftd file instead. Also instead of ftd.migration, it would be called fastn.migration.

Earlier Design

Any file can contain:

;; name is unique id of this migration
;; migrations are applied in the order specified in this file

-- ftd.migration: name

create table ..

create table ..

-- ftd.migration: name

update table ..
create table ..

If someone modifies an applied migration (name or query) it is an error. If existing migrations are re-ordered after being applied its an error. If a new migration is added in the beginning or before last applied migration, again an error.

Convetion: migration.ftd. For now we will not auto run this and someone will have to visit the /migration/ url to apply the migrations. In future the we can auto run it on save.

[amitu]

This is implemented.