Joing tables from different databases - performance issues

Hello,
What is performance difference between joining tables
1. from the same database
2. from different databases located on the same instance of MS SQL Server
3. from different databases located on different instances of MS SQL
Server (linked servers) when these instances are located on the same
physical machine
4. from different databases located on different instances of MS SQL
Server (linked servers) when these instances are located on different
physical machines and these machines contact each other through LAN
I guess, performance or variant 1 is the best and for 4 is the worst,
but if (and how big) are there differences between: 1 and 2, 2 and 3.
Thanks a lot.
MerlinThat really depends on a lot of things such as the queries
themselves and on your network configuration - issues such
as are the servers on the same switch. There is no black and
white percentage to give you. If you are concerned about
performance across servers, you may want to check the
performance tuning tips in the following article:
http://www.sql-server-performance.com/linked_server.asp
-Sue
On Thu, 15 Dec 2005 13:00:15 +0100, MerlinXP
<MerlinXP_NOSPAM@.NOSPAM_poczta.onet.pl> wrote:

>Hello,
>
>What is performance difference between joining tables
>1. from the same database
>2. from different databases located on the same instance of MS SQL Server
>3. from different databases located on different instances of MS SQL
>Server (linked servers) when these instances are located on the same
>physical machine
>4. from different databases located on different instances of MS SQL
>Server (linked servers) when these instances are located on different
>physical machines and these machines contact each other through LAN
>I guess, performance or variant 1 is the best and for 4 is the worst,
>but if (and how big) are there differences between: 1 and 2, 2 and 3.
>
>Thanks a lot.
>Merlin