I have added an external data column with secondary fields to a document library. It is filled with values from an external content type in a BDC Model. The document library items show the correct values. However I am unable to find the items in enterprise search when querying the values in the external data column (with search scoped only to the Sharepoint content source). These items can in fact be found by searching for values in all of the regular columns.
Also, searching for those values works when I search in the scope of another content source that uses the BDC Model. But I want to be able to find them in the Sharepoint content source scope as well. This scope has a scope rule that requires the items to be of
contentclass = STS_ListItem_DocumentLibrary.
Of course, I did full crawls on all content sources, which were completed successfully as well.
Why are the external data columns not searchable as Sharepoint content? Is the scope rule incorrect for this case?
Update: Further tests have shown that there is a difference in the behaviour of documents and folders. In fact, folders can be found by searching for values in external data columns. Documents however, still cannot be found. This proves that the external data columns must have been crawled, but for some reason there is no association between this data and the documents themselves in the search index. Extending the scope rule of the Sharepoint content source scope to include all content did not change anything as well.