In Web Portal, I am trying to trace the semantic mapping lineage using Designer Layer Models There is an option to expand to column level but when I click 'Expand' button, nothing happen. Why?
Explanation and Solution:
Note: Semantic lineage is not the same as data flow lineage. With data flow lineage, one specifies Column level mappings and the Table level mappings simply follow from that. With semantic lineage, a link from one Table to another does not mean that all Columns are also mapped. Thus, when you use the plus sign to expand, you do not see the Column level lineage, because there is no column level lineage in that diagram.
Now, if you instead go to the home page for one of the Columns, say customer ID, then you get to the semantic flow tb. There you will see the Column level lineage for that case, so this behavior is as expected.
If you start from Table level semantic usage lineage, then it is true that the "To Column level" option does not do much. However, if you start from Column level semantic usage lineage and collapse everything. then the the "To Column level" option is important.