topic Re: Star schema in QlikView

Star schema

Fri, 23 Nov 2012 14:15:09 GMT

Hi all,

I have a few tables and want to model them as a star schema for better perfomance.

InvoiceNo	CustomerNo
1234	345
354	654

DueDate	InvoiceAmount	CustomerNo
10/12/2012	3456	345
12/12/2012	8979	654

CustomerNo	Name	Address
345	William Bonney	null
654	John Dillinger	33 Liberty Street

How can I join just the fields InvoiceNo, InvoiceAmount and CustomerNo into one fact table? When first load all two or three fields from the tables and then join just the fields I want my machine with 8GB RAM freezes. If I ommit the joins I'm able to load the full dataset. Any help is appreciated!

Re: Star schema

jvitantonio — Fri, 23 Nov 2012 14:44:11 GMT

Try this:

T1:

LOAD InvoiceNo, CustomerNo FROM table1;

T2:

join (T1)

LOAD CustomerNo FROM table2;

T3:

JOIN (T3)

LOAD CustomerNo, Name, Address from table3;

drop fields Address, Name;

Re: Star schema

swuehl — Fri, 23 Nov 2012 15:19:40 GMT

I assume you can have multiple InvoiceNo per CustomerNo, right?

How do you want to link a InvoiceNo to a certain InvoiceAmount then, if the only key is the CustomerNo?

Re: Star schema

Mon, 26 Nov 2012 13:14:09 GMT

Thank you for replying!

This is what I'm doing, except the drop fields part.

What is the purpose of droping name and address? Can't I drop the whole T3 table?