The Data Dictionary Should Live in the ERD, Not in a Spreadsheet

Disclosure: I build Schemity, a desktop ERD tool - this post is from our blog and uses it for the examples. TL;DR: The meaning of a schema - what tables are for, who owns them, why a grouping exists - usually lives in heads, spreadsheets, or wikis that drift out of date. Schemity attaches markdown descriptions to entities, legends, and context views, shown behind a file icon on the diagram itself, so the data dictionary lives inside the ERD and stays where the schema is. You can write what a table, a group of tables, or an entire view of your schema means directly into the diagram: Schemity stores a markdown description on entities, legends, and context views, one click away behind a file icon on the canvas. The data dictionary stops being a second document you maintain next to the ERD - it becomes part of the ERD. That matters because the second document is where schema knowledge goes to die. Where does the meaning of your schema actually live? An ERD tells you what t