Inconsistent API return type when iterating over WDS 3 search results

Problem

A search for files and emails containing a word or phrase in their content or name / subject raises an InvalidCastException on processing some of the result set rows.

Detail

When iterating over an OleDbDataReader result set (C# & .Net framework 2.0.50727) from a search on an OleDbConnection to a local WDS 3 on XP Pro SP2, I get an inconsistent return type from OleDbDataReader.GetString(int ordinal). The ordinal matches with ‘DocAuthor’ in OleDbCommand.CommandText = “SELECT … DocAuthor …”. The API docs say the GetString(int ordinal) return type should be string or DBNull, but I get string[] for some rows and so assigning to a string causes an InvalidCastException. Currently I manage this by catching any InvalidCastException and skip that result set row. I notice that the OOTB search UI seems able to handle at least one of the files my code finds a problem with, the downloaded ‘Windows Desktop Search Administration Guide.doc’ in fact.

This seems like a bug to me and I submitted bug ID 250587 against the .NET Framework Library on January 8th 2007, but so far nothing has happened. So I thought I would ask this forum for their collective wisdom on this problem.

Also I need to constrain the search scope for file and email but have not seen an example of how to do that yet; does anyone know

Any help from you clever folks would be most appreciated.

Thanks

Gary