I am not sure if I get it right. What I know is Blending always does a left join ie primary data source left join with secondary data source. for eg:
primary source is
id , name
id , name1
Now when you blend on ID field , data will look like this:
id, name , name1
1, A , C
2, B ,NULL
You will not see 3, D in output
Now when you apply filter on name1(from secondary data source) on dashboard you will see "D" also in list of values but filleting out it will not make any impact on your view because it was already filtered out as part of blending.
Other than that i think everything else will behave right like when you filter out name 'A' your whole row will go , or filtering out name1 'C' again whole row will go.
Not sure if I made sense to you. Hope it helps.
That does make sense to me! Thank you for your response.
What doesn't make sense to me is when I apply the filter from the primary source, I cannot apply that filter to the sheets that have the secondary source as a primary measure.
Your question made me realize that I am not asking my original question in the correct manner.
Ahh! Now i got what you are trying to ask.
I just created one more sheet ( sheet2 , previous one let say was sheet1) by reversing the primary and secondary source in my previous example and now when i put both sheets on a dashboard , filter on 1 sheet not affecting data of other sheet.
But what is interesting is dashboard actions are working. So if you use 1 sheet as filter and you click on a data point , it will filter data for other sheet as well.
To further investigate it I created one more sheet (sheet3) same as sheet1. Now when i went to a filter of sheet1 on Dashboard and chose selected worksheet option:
the pop up comes as:
so for sheet 2 it says relationship "None"(and checkbox is disabled). So i guess when the primary and secondary sources are swapped in two sheets , Tableau can not make any relationship between them. And so it does not filter data.
That's all I could make out.
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Of course you have to have a relationship. Tableau does the best job it can to figure that out and to help but I know you have to have something in common.
That said - I asked a friend of mine the same question as I wrote this post.
He told me that you have to make sure that you use a related field between the primary and secondary sources, and you will be able to filter.
So for example:
Table 1 has the dimensions - ID, Animal, Color
Table 2 has the dimensions - ID, Color, Name
Therefore if you set this up a relationship to color and ID, the blending will work. You have to drag a common field into the viz and that is the field in which you will filter on. In this case, it doesn't make sense to bring ID into the viz but it would make sense to bring Color in.
He showed me this picture:
I did a quick search and found this article:
Thanks Scott to make it clear