Cashing Views and Queries Conceptual Misunderstanding

Question

I'm hoping that someone can help demystified this riddle for me. The OBIEE documentation is rather large and perhaps I'm being a bit impatient I will admit. However, here is a question for the experts. Once I create a repository and I connect to an external database outside of OBIEE server, in other words I have Database A but in my repository I have a connection pull data from Database B, is OBIEE really bringing data into the OBIEE server and storing it somewhere? Or is it actually doing a full select to that other database and doing all the formatting etc. I know from the WEB APP you can cache results, which I believe is different than what I'm asking.  If someone can explain this a little better or point me in the right direction in the documentation that would be very helpful.

Thanks!

mlov83 · Answer

Thank you guys. Now that makes much more sense! I really appreciate the respond.@rmoff, great article. I can't believe I did not run into this one.

Thanks a bunch!

rmoff · Answer

@Gianni Ceresa has pretty much said it all. I'd only add that if you are federating queries across both database A and B (for example, one stores sales, the other stores customer lookup data, and your end user runs a query asking for sales by customer) then OBIEE will indeed generate a query against each database, pull the data back, and do the joining/aggregation/etc necessary. Is it storing it somewhere? Kinda. It will get done in memory, and landed to disk if too big. Does is persist? No - not unless you use BI Server caching (which is different from the caching in the Presentation Services, or any front-end cache too).

The section (and maybe more) "What Happens When an OBIEE Query Runs?" might help you:

Gianni Ceresa · Answer

OBIEE doesn't store data.

So taking it simply if you run a report / dashboad using Database B as source OBIEE will generate a query to Database B, get the data back, format it and send it out to your screen (over simplified process).

There is cache that can be enabled in OBIEE, if you enable the cache OBIEE can store the result he got from your database in the cache and if the same or similar query requiring a subset of the cached data is executed OBIEE will be aware he can actually use its own cache and will not ask your Database B anything.

But officially OBIEE doesn't store any data. You can't really consider cache as storage because it will not cache your Database B objects but will cache the result of executed queries by OBIEE.