You can save a diagram by choosing either the Save or Save As commands from the File menu. Database Designer for PostgreSQL saves the diagram into a specially formatted .pdd file, which contains the diagram and its properties. You can also save the current diagram by clicking on the Save () button in the Standard toolbar.
If you are saving a diagram for the first time, select the Save command, then type in a "file name" for your diagram and specify the location on your computer where you want to save it. Diagram file names must meet the requirements of a standard Windows filename.
If you are saving a diagram that was already saved, use the Save command to replace the file contents or the Save As command to save the diagram with a new name or to a location.