topic Re: fact tables in QlikView

fact tables

ashokraju — Wed, 25 Nov 2020 16:16:04 GMT

i have three fact tables and multiple dimension tables.how we create star schema.

Re: fact tables

migueldelval — Fri, 01 Jul 2016 06:38:38 GMT

Hi Ashok,

If it´s possible join fact tables in only one, and after link dimensión tables with only one field to avoid Syn links.

If you want send me a sample of your data and I could help you.

Regards

Miguel del Valle

Re: fact tables

PrashantSangle — Fri, 01 Jul 2016 06:43:16 GMT

Hi,

concat 3 fact table to one.

Use concatenate to concat

Regards

Re: fact tables

ashokraju — Fri, 01 Jul 2016 06:46:06 GMT

thanku

Re: fact tables

jyothish8807 — Fri, 01 Jul 2016 06:46:56 GMT

Hi Ashok,

There are two ways to do this:

1. Try to concatenate all the facts tables if possible.

2. Create link table

Go through this, hope it will be helpful:

MASTERTABLE (LINK TABLE or Concatenated FACT Table)

Regards

Re: fact tables

gautik92 — Fri, 01 Jul 2016 07:30:08 GMT

creating a link table for all the three fact tables and make that link table as a fact table

Re: fact tables

effinty2112 — Fri, 01 Jul 2016 10:31:10 GMT

Hi Ashok,

It would help if post an image from your table view with your dimensional tables and your three separate fact tables. There will be more than one way of doing this. My approach is usually to concatenate your fact tables but this may involve moving some of your fields around.

Suppose you have two fact tables with a one to many relationship such as order header and order items with a number of dimensions associated with your header table, such as Customer and others, the two fact tables associate on a field like OrderID.

"Move" the Customer field into the Items table by something like

MappingCustomerRef:

Mapping

LOAD

OrderID,

CustID

Resident OrderHeaders;

Left Join(Items)

LOAD DISTINCT

OrderID,

ApplyMap('MappingCustomerRef',OrderID,'Missing') as CustID

Resident Items;

DROP Field CustID from OrderHeaders;

Now the Customer dimensional table will associate with the records in the Items table.

Do this for all dimensions associated with the header table until the Header table has only one association, that is with the Items table on the field OrderID. At this point you can concatenate the two tables.

A final point: star schemas are all very well and easy to understand but I wouldn't get obsessed with always obtaining that model. Sometimes there is a high price to pay in memory usage when creating large fact tables and performance may in fact suffer.

Cheers

Andrew

Re: fact tables

ashokraju — Fri, 01 Jul 2016 15:46:43 GMT

thanku