Re: OT: Ways of managing changes to a database's structure during a project.

[podian]

in reply to OT: Ways of managing changes to a database's structure during a project.

As I see it this is a general database based project problem but I have not seen much discussion on it here or elsewhere (please correct if wrong). For the record I am using Postgres 7.4.

It is also an standard upgrade problem - What to do when you go from one version to the next version which changes the datbase structure.

You have more chanllenges when doing it on a live system where the database can't go down (or may be can go down only for few minutes).

I agree that each change must be versioned so that, for example you can go from version 1 to 3 (skipping version 2).

One interesting problem to consider is:

Say a customer has version 1.

you made a table change (new column X) in version 2

You made another table change in version 3 (new column Y

Now your version 3 SQL will have only 'add column Y'

To upgrade from version 1 to 3, you need to combine both changes or upgrade to version 2 first and then upgrade to version 3