Re: [HACKERS] Re: ORDBMS

On Fri, 28 Jan 2000, Tom Lane wrote:

> The Hermit Hacker <scrappy@hub.org> writes:
> >> What I don't understand yet is whether the contents of table
> >> "address" have any connection to the data stored in table "person".
> >> If not, why must I create a table in order to define a datatype?  Seems
> >> like a separate CREATE DATATYPE command would make more sense...
> 
> > Not quite an answer to your question, but my guess is that 'address
> > ADDRESS' would contain a pointer (OID) to the address table ... so the
> > person table would be realtively small in comparison to the address table
> > ...
> > The way I look at the above, its a 'JOIN' at table create time, based on a
> > unique value, the OID ... 
> 
> Hmm.  OK, that makes sense, because I know I've seen places in the code
> that think that any "set type" is represented as an OID.  I never
> understood what that was all about, but in this context that would be
> what would happen.  Assuming that this facility is the same as what
> the code calls a set, that is.
> 
> So, if I looked into table address, presumably I'd find rows
> corresponding to each value that is (ever has been?) stored in another
> table with an ADDRESS column.  How do no-longer-useful values get
> cleaned out of the address table, do you suppose?

An internal trigger?  'ON DELETE FROM person DELETE FROM address where
OID=?' ?


Marc G. Fournier                   ICQ#7615664               IRC Nick: Scrappy
Systems Administrator @ hub.org 
primary: scrappy@hub.org           secondary: scrappy@{freebsd|postgresql}.org