diff --git a/Notes.md b/Notes.md
index e16a96a..e1ac35f 100644
--- a/Notes.md
+++ b/Notes.md
@@ -54,3 +54,9 @@ I think we should have empty nodes which are just used to group dependencies,
 e.g. something like `table_x_complete` which depends on `table_x` and all its
 columns, contraints, indexes, data, etc. so that other nodes can just depend on
 `table_x_complete` and don't have to bother about the details.
+
+I don't have a good ideas for data changes yet. For example I may want
+to change the value of a (non-PK) column for one or more rows. Easy in
+SQL, not easy in a generic way without reinventing SQL. 
+Idea for the simple case: data_update key={} new={}.
+Maybe allow arbitrary SQL for the complex case. But must be idempotent.