O Achilleus Mantzios έγραψε στις Sep 20, 2005 : > > Hi, > > I think i have reached a point in my PgSQL years > that i am seriously thinking of using inheritance. > > The situation is simple: An new entity (tanker vessels crew) > is about to be modeled, and i suspect > there will be a future need to include > the rest of 'workers' besides 'sailors', > IOW i suspect a future need to generalize. > > So i am thinking of a two-level tree hierarchy, > where there is a simple table emp (employee), > and a direct child 'tankerscrew'. Later > there may be 'masons', 'office_employees' > and so on.
Each table may be managed by its own applications, whereas the accounting software will only need to read and *update* the generic top level 'employee' table. That would be great but unfortunately it isnt how it works in PostgreSQL currently... If PRIMARY KEYS were to be shared, a great future (real) feature would be a "isinstanceof" -like function on the PRIMARY KEY, which tells if a row of the specific PK is from a certain table in the hierarchy. > > The problem is that while i find this approach > attractive, i have never used PostgreSQL > inheritance exhaustively and in production scale. > > Furthermore, i also feel that not many > people have used inheritance in a massive fashion > (besides playing with a test db). > > Of course i can do it with separate uncoupled tables, > that can be later related with some views. > > So that leads to the final question: > -What are the main PROs of inheritance that cant be beat > by other solutions, and > -Are there any traps someone must have in mind when he > prepares for such a design? > > Thanx in advance. > -- -Achilleus ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
