Re: SQL: Joining on three part names.

Regarding distributed joins...

Somebody mentioned MS SQL having this functionality via linked servers.

While true, there is a catch...

In MS SQL Server, when using 4 part names directly, ex:
select * from FALCONPROD.S10316ZM.HLTHPRDFIL.CUSTOMP where locnbr = '00335';

It pulls back the entire table and does the WHERE locally.

You have to using OPENQUERY to send the SQL statement itself to the remote
server and get back just the rows you are interested.
select * from openquery(FALCONPROD, 'select * from customp where locnbr =
''00335''');



On Tue, Feb 17, 2015 at 3:31 AM, D*B <dieter.bender@xxxxxxxxxxxx> wrote:

@federation server: it's not running on as400, you would need an
additional non as400 server with DB2 and its very expensive
@commercial pendant to ArdGate: its called DBGate by Razlee, but I don't
think, that they have too much installations. ArdGate came out earlier and
its easier for open source to get installations.
@join in distributed databases: IMHO distributed joins are not as good as
it looks at the first glance. Optimisation and performance is critical and
DB2/400 provided capabilities fro scripting solutions long before three
part alias (that's only a marketing gag). You could pull subsets of data
from diffrent systems very easy, using STRQMQRY RDB(xxx) OUTFILE(yyy)
redirecting the output to the local system and join the subsets of data
afterwards. If it's not possible to reduce the amount of data transferred
this way, another strategy would be replication (by triggers for instance)
to a remote system. Using ArdGate you could implement both strategies even
with by the fly generated scripts. Commercial solutions are going this way
too and sometimes they are pulling even big tables completely from one
system to the other, before joining the data.

D*B
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