Best Way to Filter Dimension Table to Only Values Used in Fact Tables

[rlussky]

Hello,

I have a fact table that refers to about 30 of a dimension table's 100 keys. What is best practice to only load dimension table keys that are in the fact table?

I can get what I want by

* referencing the (VERY LARGE) fact table

* removing all columns but the foregin key column

* removing duplicates

* merging (inner join) with the dimension table

I was thinking there has to be a less expensive way than this though. It would be nice to not have all the unnecessary dimension table data. 

Thanks!

[Anonymous]

Hi @rlussky ,

Could you tell me if @lbendlin 's post helps you a little? If it is, kindly Accept it as the solution to make the thread closed. More people will benefit from it.Hope to hear from you‌‌😀

Best Regards,
Eyelyn Qin

[lbendlin · Accepted solution]

Use Power Query and Query folding to pre-filter your data, or do that in your data source.

NOTE:  yes, you should reduce the amount of data you load into Power BI as early as possible, but not earlier. Take some time to consider if you are destroying information by applying this filter.