Invoice/Invoice Details

[PowerBI123456]

Hi,

I have a large table (30 columns) and 1 billion+ rows that has the invoice details at the invoice level (i.e. customer name, invoice number, date, etc.) and the invoice detail (line item costs by item). Sometimes each invoice can have anywhere from 1-100 line items. I read that its best not to split these 2 tables up and instead denoramlize and keep it as one big one. Is that right? Is there any cases where you should split it up? 

Wouldn't it take extra space since the invoice level details are being repeated for each line item and takes up space? 

Thanks in adavance!

[AllisonKennedy · Accepted solution]

Which articles have you read already? It does require duplicating the data, but puts less load on the relationship. See this explanation: https://www.sqlbi.com/articles/costs-of-relationships-in-dax/

If your invoice table is very large, it can be better to denormalize it.

[PowerBI123456]

@AllisonKennedy Thanks! That was the one I was looking as well. I got concered with the size of the table, but seems like the relationship is more important. Thanks!