When I said occasional in the last blog - I didn't specify the time interval - so here is a second post in as many minutes!
There are a number of ways to tidy a cluttered diagram. Sometimes you don't want to see all the columns/constraints in the table shape, or perhaps you only want to see some of the columns - the keys or the most important columns:
View As -> Compact
Select shapes in a diagram and use this context menu to completely remove any columns or constraints from the shape
Hide Selected Shapes
If you want to show only some of the members of your shape (for instance only the keys and major columns in a table) select members you want to hide and use this context menu. The members are cut from the diagram but are still available to you through the shape editor. To see all the members again use Show All Hidden Members
Tools -> Preferences -> Diagrams -> Database
Under this node you will find many different options for your database diagram - you can change font, shape colors for many different database shapes. For instance - select Table from the dropdown list and uncheck Show Constraints if you want to exclude them from the diagram. Note that changes made in this way only apply to new shapes added to a diagram. So it's good practice to check your preferences before you start work on a diagram