In message <01BCF103.FB25DDD0@ashokpc.ntd.comsat.com>, Ashok Rao writes:
> I've heard that Oracle Database applications have "problems" when they are ru
> n over satellite
> links. Does anyone have any more information to offer on this ?
>
> Thanks
>
> Ashok Rao
> Senior Scientist
> Network Technology
> COMSAT Labs
> rao@ntd.comsat.com
There is a lot of control available over the granularity of locking.
You can choose a very fine granularity, making very small operations
atomic and locking out others for a minimal time. This works fine on
a LAN but is very slow over a WAN, not just a satellite link. This is
true of any of the major RDBMS. (It is true of any RDBMS but the not
so majors tend not to have the level of control). The alternate is to
make larger operations atomic, locking as much as possible, doing as
much work as possible in a single transaction, and then unlocking.
This can be slower on a LAN with many stations competing for access to
the database (but often isn't) and is generally *much* faster on a
WAN. Just don't lock and wait for user input.
We saw this sort of problem with customers using another major RDBMS
and they blamed poor performance on "the net" and/or the RDBMS when it
didn't perform well over a very low loss 20 msec RTT path as it did on
the benchtop. Just imagine what more than 500 msec RTT would do to
such an application. Changing the granularity of locking operations
in the application solved the problem for this particulr application.
Curtis
This archive was generated by hypermail 2b29 : Mon Feb 14 2000 - 16:14:33 EST