Re: [HACKERS] Database replication... - Mission Critica

On 4 Nov 2002 at 12:23, Mikheev, Vadim wrote:

> > My presumption would be that if you initialize 2 databases to
> > a known identical start, have all the same triggers and rules
> > on both, then send all queries to both databases, you will
> > have 2 identical databases at the end.
>
> This is wrong assumption. If
>
> 1st client executes UPDATE t SET a = 1 WHERE b = 2;
> 2nd client executes UPDATE t SET a = 2 WHERE b = 2;
>
> at "the same time" you don't know in what order these
> queries will be executed on two different servers (because
> you can't control what transaction will lock record(s)
> for update first).

I guess we would need two phase commit in this case. Then it could be
guaranteed.

Bye
Shridhar

--
There comes to all races an ultimate crisis which you have yet to face.... One
day our minds became so powerful we dared think of ourselves as gods. --
Sargon, "Return to Tomorrow", stardate 4768.3