Datamapper DataMapper

Comments and changes to this ticket

• 

  Jonathan Stott (namelessjon) November 30th, 2008 @ 07:26 AM

  • Assigned user cleared.
  • Tag set to “auto_upgrade, migrations, suggestion”
  • Milestone cleared.
  • State changed from “new” to “open”
• 

  Dan Kubb (dkubb) January 8th, 2009 @ 02:14 PM

  • State changed from “open” to “not-applicable”

  Closing this ticket as per: http://is.gd/eOHY

  I actually think this is a great idea, and think it would be better to open a thread on the mailing list to discuss this and similar approaches to auto_upgrade where non-destructive changes can be done.

  Ana: Do you mind opening a thread on the mailing list and referencing this ticket?

  I think things like adding/removing indexes, lengthening columns, loosening constraints (like changing NOT NULL to allow null), adding/changing default values could all be done by auto_upgrade.

  In fact given some planning I think it might be possible to do destructive changes safely. Consider a case when the field length is reduced from 100 to 50 characters max. We could do a SELECT MAX(LENGTH(column)) FROM table to see if anything exceeds the 50 character max.. if not, then we know we can safely change the table.

  To make some of this work, I would like to discuss on the mailing list a sort of dm-reflection plugin that would know how to reflect on the state of the 3 databases we support, so we can know stuff about the table structure, and table contents (like knowing the maximum length value stored in a column), and make decisions about how to safely alter the table. We could even use dm-reflection to generate models from an existing database. Lots of possibilities here.