I have a table named table_Users: CREATE TABLE table_Users ( UserID character(40) NOT NULL default '', Username varchar(256) NOT NULL default '', Email varchar(256) NOT NULL default '' etc... ); The UserID is a character(40) and is generated using UUID function. We started making making other tables and ended up not really using UserID, but instead using Username as the unique identifier for the other tables. Now, we pass and insert the Username to for discussions, wikis, etc, for all the modules we have developed. I was wondering if it would be a performance improvement to use the 40 Character UserID instead of Username when querying the other tables, or if we should change the UserID to a serial value and use that to query the other tables. Or just keep the way things are because it doesn't really make much a difference. We are still in development and its about half done, but if there is going to be performance issues because using PK as a String value, we can just take a day change it before any production as been started. Anyway advice you can give would be much appreciated. Postgres performance guru where are you?
