Don't hold it against me, but I have a fond memory of MS SQL Server Management Studio. I could very easily generate an ERD diagram from an existing database. Tables, relationships, the works. You could even use the diagram to edit the database structure.
I can't find such a tool in pgAdmin III. Am I missing something? It seems there isn't one built-in. Is there a plugin? Or a separate tool?
(I have found references to using Dia and other tools to model first and then generate the SQL to create the database. This is nice, but secondary to my primary goal which is to generate a diagram from an existing PostgreSQL database. And to truly replicate Management Studio functionality, the application would have to work in both directions.)
Best Answer
Schema Crawler
http://www.schemacrawler.com
"SchemaCrawler is a free database schema discovery and comprehension tool... output the schema and data in a readable text format. The output serves for database documentation, and is designed to be diff-ed against other database schemas. SchemaCrawler also generates schema diagrams."
deb installer: https://github.com/adriens/schemacrawler-deb
Licensing: https://sualeh.github.io/SchemaCrawler/license.html (GPLv3)