hasta_l3_at_hotmail.com wrote:
> vc wrote :
>
>> hasta_l3_at_hotmail.com wrote:
>> [...]
>>> More concretely, the whole list structure is being changed,
>>> and the change should be atomic with regard to other
>>> operations that may also change the structure. However,
>>> the short transactions - which dont care about the structure -
>>> should not block.
>> So only the transactions modifying the entire list would select for
>> update the list header and therefore be executed serially, the
>> smaller transactions that do not care about the list structure would
>> proceed in the usual way without locking the header first. What is the
>> problem ?
>
> Assume a (long) restructuring operation L modifies
> (a) some fields of the list header row in the master table, then
> (b) some fields of every list line row in the children table, including
> -say - row R.
>
> Assume that a short transaction S modifies
> (a) some (other) fields of the list line row R.
>
> If L is in a single long transaction, then it will block S if S happens
> to want to modify R after L did it.
Look up PRAGMA AUTONOMOUS_TRANSACTION. It may help.
--
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace x with u to respond)
Puget Sound Oracle Users Group
www.psoug.org
Received on Wed Nov 01 2006 - 10:04:56 CST
