In the 'Dependent Data mart' case, there is an ETL layer to extract
the data from the central Data Warehouse to adapt and Load onto the
'Data mart'.

Assume that the 'Data warehouse' and 'Data mart' run on separate
physical servers. In such a case, where does the ETL layer (which is
used to load onto Datamart from Datawarehouse) fit better? Should it
be part of 'Data warehouse' box, or the 'Datamart' box? Why?

On Mar 18, 11:29*am, guser78 <qazmlp1... (AT) rediffmail (DOT) com> wrote:
"Should it be part of 'Data warehouse' box, or the 'Datamart' box?"

Neither of them. It should be on a separate ETL server with the ETL
tools and processes installed on it (and a lot of free HD space too).

HTH.

Cheers.

Carlos.

On Mar 18, 8:03*pm, Carlos <miotromailcar... (AT) netscape (DOT) net> wrote:
having only 2 servers (1->DWH, 1->Datamart, ETL->where?)?

On Mar 18, 8:03*pm, Carlos <miotromailcar... (AT) netscape (DOT) net> wrote:
I agree with that. But, what do you do when you have the option of
having only 2 physical servers (1->DWH, 1->Datamart, ETL:where?)?

On 19 mar, 10:32, guser78 <qazmlp1... (AT) rediffmail (DOT) com> wrote:
"I agree with that. But, what do you do when you have the option of"
having only 2 physical servers (1->DWH, 1->Datamart, ETL:where?)?"

At a first glance, on the DataMart machine, but it depends. I would
resume it as "...where the harm is smaller" If you put the ETL on the
Datamart machine and the performance decreases dramatically, and you
put the ETL on the DW machine and it can cope with the overhead (DW
performance, general performance, filesystems, etc) then put it there.

But I would avoid to put it on the DW machine (been there, done
that...)

HTH.

Cheers.

Carlos.

@e7g2000yqf.googlegroups.com>, guser78 says...

Given that restriction, I'd usually go "on the target rather than the
source", because some of my ETL processes are designed so that the
transform and load components should only occur if a full extract is
successfully completed, and it's easier to deal with network outages in
these instances if ETL is on the target.

GM