Re: [HACKERS] Re: ORDBMS

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?
        regards, tom lane