why DocNo instead of docId uniqueidentifier ROWGUIDCOL NOT NULL, ??



Unfortuantly there isn't one simple answer. I would start with what you've suggested yourself, but then I'd load up the tables with appropriate quantities of data and kick them through profiler (SQL Server Query Execution Plan Analysis) and look at the generated execution plan. Benchmarking really is the only way to work it out.

If you get index seeks, then all is good: no more work really needed. If you have index scans, then see if the indexes can be tweaked to turn them into seeks. If you see any bookmark lookups in the execution plan, consider having other columns into the index so the index itself covers the query.

give me a couple of lines of the data you have ( insert statements);