Document size after changing model

[ramonarcusa36]

Hey guys.

There is something I don't understand. My model consists of one big fact table (around 40 million rows) and approximately 20 dimension tables (products, customers, all those things).

I have made a slight change in my model: I have left joined my fact table to some simple dimension tables. I got a recommendation telling me it's usually a better practice to include the descriptions in the fact table, so I tried. And contrary to what I expected, my document size has decreased a lot! From 3 GB to 1.6 GB.

Is this normal? What is QlikView doing here that results in reducing the file size after including text descriptions in a big fact table? Shouldn't it increase its size because long descriptions are now repeated many times?

Thanks!

[ramonarcusa36]

Manuel said it's better to use ApplyMap to add descriptions to fact tables... but will I lose optimized load if I do it?

About performance, Qlik has recommended us to use as few dimension tables as possible, integrating their fields in the fact table. That's what I'm trying to do. I've always used a star model, as normalized as I can in order to have every description in its right place. You're making me think it's not always better, it depends... but on what?

If you guys suggest I shouldn't care too much about the document size as long as it's working properly, I'll follow your suggestion.

Thanks.

[Anonymous]

Hi ramon,

Yes, you will loose optimized load from QVD. If you have incremental load, store your QVD with Applymap done.

If you have more than one dimension for one fact, this dimension will be on another table. But if you have one dimension table with code and description, is better to include in fact table.

Regards.