Re: IN PLACE UPDATE of an object type?

Am Thu, 03 Feb 2005 12:45:50 +0100 schrieb Michael Schaefers <schaefe3_at_cs.uni-bonn.spam-remove.de>:

> Consider the following example TYPE:
>
> CREATE TYPE foo AS OBJECT (
> state INT,
> b BLOB,
>
> MEMBER FUNCTION difficultFunc RETURN INT,
> MEMBER FUNCTION easyFunc RETURN INT
> );
>

>
> !!!BUT: Both foo instances work on the same BLOB and therefore the
> instance stored in the database has become inconsistent: the "state"
> attribute says "unstructured", but
> the BLOB data is "structured"!!!
>

I think you have to implement a mutex protocol to access the BLOB. The evtl. updating function difficultFunc has to place a lock while working. Locking may be done by dbms_lock() or physical on the tables row.
Both functions easyFunc and difficultFunc have to wait until the lock is released.

-- 
Frank Piron,
defrankatkonaddot
(leftrotate two)