-----Original Message-----
From: Maurice Gittens <mgittens@gits.nl>
To: hackers@postgreSQL.org <hackers@postgreSQL.org>
Date: zondag 5 april 1998 21:47
Subject: [HACKERS] On improving OO support in posgresql and relaxing oid
bottleneck at the same time
>Hi,
>
>I'm currently under the impression that the following change in the
>postgresql system would benefict the overall performance and quality
>of the system.
>
> Tuples for a class and all it's derived classes are stored in one file.
>
>Advantages:
-- cut --
>
>
>Disadvantages
>- sequential heapscans for tables _with_ derived classes will be less
>efficient
> in general, because now some tuples may have to be skipped since they
>may
> belong to the wrong class. This is easily solved using indices.
>
>- slight space overhead for tuple when not using inheritance.
> The space is used to tag each tuple with the most derived class it
> belongs to.
>
One extra disadvantage of this is that multiple inheritance is only
easily supported if bases classes being inherited from have a common
top most base class. In which all tuples are stored. Otherwise
we'll storagefile independant oid's will become necesary again.
So loosely speaking it still allows for multiple inheritance but only within
a common hierarchy.
With regards from Maurice.