I'm trying to create a set of files that describe project data and have a
column view block in a summary file, but the columnview is only picking up
one project, and I need it to pick up all.

P1.org and P2.org are two sample project files, and MasterP.org is the
summary file.

P1.org:

#+COLUMNS: %15PROJ(Project) %35ITEM(Task) %Start %End %8Effort{+} %TODO

* Tasks
  :PROPERTIES:
  :ID:       simple
  :PROJ:     P1
  :END:

** TODO Phase 1                             :testbed:
   :PROPERTIES:
   :End:      [2014-03-19 Wed]
   :Start:    [2014-03-11 Tue]
   :END:
** TODO Phase 2                             :testbed:
   :PROPERTIES:
   :Start:    [2014-03-20 Tue]
   :Effort:   32h
   :End:      [2014-04-01 Tue]
   :END:
** TODO Phase 3                             :testbed:
   :PROPERTIES:
   :Start:    [2014-04-02 Fri]
   :Effort:   20h
   :End:      [2014-04-11 Fri]
   :END:

P2.org:

#+COLUMNS: %15PROJ(Project) %35ITEM(Task) %Start %End %8Effort{+} %TODO

* Tasks
  :PROPERTIES:
  :ID:       simple
  :PROJ:     P2
  :END:

** TODO Phase A                             :testbed:
   :PROPERTIES:
   :Start:    [2014-03-24 Mon]
   :Effort:   10h
   :End:      [2014-03-24 Mon]
   :END:
** TODO Phase B                             :testbed:
   :PROPERTIES:
   :Start:    [2014-04-23 Wed]
   :Effort:   10h
   :End:      [2014-04-23 Wed]
   :END:

** TODO Phase C                             :testbed:
   :PROPERTIES:
   :Start:    [2014-05-13 Tue]
   :Effort:   10h
   :End:      [2014-05-13 Tue]
   :END:

MasterP.org:

When I execute MasterP.org with C-c C-c, I get:

#+COLUMNS: %15PROJ(Project) %35ITEM(Task) %Start %End %8Effort{+} %TODO

* Table
#+BEGIN: columnview :hlines 1 :id "simple"
| Project | Task                 | Start            | End
| Effort | TODO |
|---------+----------------------+------------------+------------------+--------+------|
| P2      | * Tasks              |                  |
| 30.0   |      |
|         | ** Phase A :testbed: | [2014-03-24 Mon] | [2014-03-24 Mon]
| 10h    | TODO |
|         | ** Phase B :testbed: | [2014-04-23 Wed] | [2014-04-23 Wed]
| 10h    | TODO |
|         | ** Phase C :testbed: | [2014-05-13 Tue] | [2014-05-13 Tue]
| 10h    | TODO |
#+END:

I want to see the data for P1, too, with the total effort at least being
summed by project. If I could also get the total effort across projects, so
much the better!

What do I need to change?

I discovered it works if I have unique :id entries for P1.org and P2.org
and then create two tables in MasterP.org. While that could work, it does
lead to two refinements to the question: how can I merge the two tables,
and is there a way to do it without distinct :id entries?

Thanks,

Bill

-- 
Bill Harris
http://facilitatedsystems.com/weblog/