Re: inserting to a multi-table view

On Tue, Jun 17, 2008 at 11:50 AM, Richard Broersma
<richard.broersma@gmail.com> wrote:
> While your individual update rules are firing for each of your tables
> from T1 thru T[n] to change your OLD row to NEW.  Another client could
> also at the same time be updating any of the other tables before and
> after your update Rules take affect.  The net result is that, some of
> what you've changed could over write what the other client commited.
> And some of what you've commited could be over written by what the
> other client wrote.  The end result is that the view's virtual "row"
> appears to be left in an inconsistant state.

Got it; thanks.

> Basically what you want to achieve is something like:
>
> begin:
> Select for update table T1 where id = old.id;
> Select for update table T2 where id = old.id;
> Select for update table (...) where id = old.id;
> Select for update table T[n-1] where id = old.id;
> Select for update table T[n] where id = old.id;
> if all the needed row lock are aquired, then
>  begin the updates
> else rollback
> commit;

Would it be possible to actually do something like this in an update
rule?  You couldn't write the "begin/commit", but it seems that you
wouldn't need to either, since the UPDATE command invoking the rule
will be wrapped in its own begin/commit (automatic or explicit).

Mike