On Wed, 2002-06-19 at 16:42, Thomas Lockhart wrote:
> > It seems like a little more powerful version of PGs INHERITS
>
> What makes it "more powerful"?
> I'd guess that it is an attribute copy
> rather than a declaration of inheritance and could be based on our
> existing "create table as" feature.
I said "a little" more powerful :)
You can specify where the "inherited" table fields are placed which you
cant when using INHERITS.
I think that 95% of current use of INHERITS is in cases where you don't
actually want inheritance :)
Regarding which you can probably move (S111: ONLY in query expressions)
to supported, with a notice that we dont support (single-inheritance)
UNDER but have our own notion of multiple inheritance.
I have ideas how to implement UNDER (put everything in one table so that
primary keys et. al. are more easyly inherited) but it will be viable
only after the same obstacles that fast DROP COLUMN are overcome.
> > I can see some features that are not listed in neither of your feature
> > lists, like
> > * ON COMMIT <table commit action> ROWS
> > * <subtable clause> ::= UNDER <supertable clause>
>
> Hmm. I worked from the SQL99 draft document we have found on the web.
I used the file ansi-iso-9075-2-1999.pdf from
http://www.cse.iitb.ac.in:8000/proxy/db/~dbms/Data/Papers-Other/SQL1999/
which has a fat red FINAL stamp on the front page, but I'm not sure how
legal it is to download it :)
> Hopefully the list is not completely orthogonal to the released
> standard; it took several hours to transform the list and to look
> through it for a first cut :(
--------------
Hannu
