Rails - Sep 2006 - understanding rails transactions.

Hi,

I''m a bit confused about Rails transactions.  Are these Rails 
transactions:

Model.transaction do
...
end

or does the above code actually start a database transaction?  If this 
starts a db transaction, what sort of db transaction does this start?  I 
would not want serializable transactions as this would be expensive.  If 
this starts a Rails application level txn, is there a way to start a db 
level txn and why would anybody use an application level txn if 
something like this exists in Rails.

Thanks,

Sam

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On Friday 29 September 2006 05:36, Sam Donaldson wrote:
> Hi,
>
> I''m a bit confused about Rails transactions.  Are these Rails
> transactions:
>
> Model.transaction do
> ...
> end
>
> or does the above code actually start a database transaction?
The outermost of these blocks starts a database transaction. Leaving the 
block normally will commit the transaction, leaving it with an 
exception will rollback the transaction.

When transaction blocks are nested, in the same method or inside called 
methods, the inner transaction blocks neither start nor end 
transactions.
> If 
> this starts a db transaction, what sort of db transaction does this
> start?  I would not want serializable transactions as this would be
> expensive.
Rails just sends BEGIN/COMMIT/ROLLBACK to the database without an 
isolation level. If you want any specific one, you have to set it by 
other means.

Michael

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Michael Schuerig
mailto:michael-q5aiKMLteq4b1SvskN2V4Q@public.gmane.org
http://www.schuerig.de/michael/

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