Re: Some newbie questions

On Sun, 7 Sep 2008, M2Y wrote:

> Why does a replication solution need log shipping and why cant we just
> ship the transaction statements to a standby node?

Here's one of the classic examples of why that doesn't work:

create table x (d decimal);
insert into x values (random());

If you execute those same statements on two different nodes, they will end
up with different values for the random number and therefore the nodes
won't match anymore. A similar issue shows up if you use functions that
check the current system time, that will be slightly different between the
two: even if the clocks are perfectly synced, by the time the standy
received the transaction it will be later than the original.

--
* Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD