Robson Miranda wrote:
>
> I was thinking in a major rewrite of the PostrgreSQL transaction
> system, in order to provide less tuple overhead and recoverabilty.
>
> My first goal is to reduce tuple overhead, getting rid of xmin/xman and
> cmin/cmax. To provide this functionality, I'm planning to keep only a
I need in xmin & xmax for multi-version concurrency control...
Let's decide what should be implemented in 6.5...
> To address the problem of non-functional update, I pretend to store a
> command identifier with the tuple, and, during update, see if the cid of
> a tuple is equal of the current cid of this transaction (like we do
> today).
cmin & cmax very simplifies implementation of data changes
visibility rules - I'm not sure is it ever possible to
do this having only one attribute for command id,
keeping in mind triggers, (PL/)SQL-funcs...
Vadim
