Re: updateable cursors & visibility

Bruce Momjian wrote:
>
> Peter Eisentraut wrote:
> > Bruce Momjian writes:
> >
> > > One idea is to require FOR UPDATE on the cursor --- while that prevents
> > > other transactions from changing the cursor, it doesn't deal with the
> > > current transaction modifying the table outside the cursor.
> >
> > That would only keep existing rows from being deleted but not new rows
> > from being added.
> >
> > > One idea is
> > > to have UPDATE/DELETE WHERE CURRENT OF behave like UPDATE/DELETE do now
> > > when they find a row that is locked by another transaction --- they wait
> > > to see if the transaction commits or aborts, then if committed they
> > > follow the tid to the newly updated row, check the WHERE clause to see
> > > if it still is satisfied, then perform the update. (Is this correct?)
> >
> > Surely it would have to do something like that, but that's a matter of the
> > transaction isolation, not the sensitivity. It doesn't do anything to
> > address the potential problems I mentioned.
>
> Well, a unique constraint on the row would see your other INSERT. I
> don't see how making an INSERT visible in the cursor would help us, and
> I don't see how we would implement that except by rerunning the query
> for each fetch, which seems like a bad idea.

I don't understand what you two are discussing.
What's is SENSITIVE, INSENSITIVE or ASESNSITIVE ?

regards,
Hiroshi Inoue
http://www.geocities.jp/inocchichichi/psqlodbc/