Re: cursors outside transactions
От | Neil Conway |
---|---|
Тема | Re: cursors outside transactions |
Дата | |
Msg-id | 1047961893.19385.62.camel@tokyo обсуждение исходный текст |
Ответ на | Re: cursors outside transactions (Hiroshi Inoue <Inoue@tpf.co.jp>) |
Список | pgsql-hackers |
On Mon, 2003-03-17 at 22:52, Hiroshi Inoue wrote: > I have never meant (1) by cursors outside transactions. I'm sorry, I don't understand. > BTW why are updatable and sensitive cursors easier > to implement using (2). (Note that I haven't looked into implementing either feature in depth.) My guess is that updateable cursors would be easier with an MVCC-based approach because the executor would still be accessing the data that is being returned. So subsequently updating the tuple would be easier (say, based on its TID), as you could be sure that whatever means you used to ensure the tuple was OK for reading would go most of the way to ensuring that it was OK for writing. Sensitive cursors would be easier to implement just due to the nature of sensitivity: if you make a separate copy of the tuples in the tuplestore, how do you check to see if they have been concurrently updated? Note that neither of these points carries much weight with me: if and when someone actually steps forward to implement either feature, we can take it into account. I'm personally planning to do updateable cursors after holdable ones, but only for the non-holdable case (i.e. updateability and holdability will be mutually exclusive). Cheers, Neil
В списке pgsql-hackers по дате отправления: