How to modify database inside a transaction in before(:all)?

[Rodrigo Rosenfeld Rosas]

I have a set of examples that should run with a specific set of records in the database.

Since setting those records is an expensive operation I'd like to perform it just once per context.

For example:

context 'sample tree' do
    before(:all) { create_tree_records }
   
    example ...
end

The problem with this is that while before(:each) and the examples will run in a transaction that will be rolled back at the end of each example, that won't happen to the records created/modified by the before(:all) block.

It seems my database vendor (PostgreSQL) supports nested transactions (savepoints):

http://www.postgresql.org/about/

I should also notice that I'm using Sequel and it seems that transactions are reentrant in Sequel:

http://cheat.errtheblog.com/s/sequel/

Database#transaction is re-entrant:

  DB.transaction do # BEGIN issued only here
    DB.transaction
      dataset << {:first_name => 'Inigo', :last_name => 'Montoya'}
    end
end # COMMIT issued only here

So, this logic wouldn't work for me. I need a save point in a before(:all), so that I'd restore it on a before(:each).

Is there any recommendation to make this work in my specs?

Thanks in advance,
Rodrigo.