updtaing through a virtual column of a view

I had read several articles of internet that compression/decompression of blob can be implemented transparently (i.e., without modifying third party code)
using views and instead of triggers for insert/delete/update.

I have a table blobtble( in third party application) which I renamed to
blobtable_orig:

create table blobtable_orig
(
body_txt blob
);

I want to compress blob when storing in database and uncompress it when selecting it. My code comes from third party, so I cannot make any changes except I can modify database schema such as create triggers and views.
I had created a thread on this sometime ago but now I am starting another thread to point the specific problem with update.

I defined a vlwe:

create of replace view blobtable as
select uncompress(body_txt) body_txt from blobtable_orig

I create instead of triggers for delete/insert/update, in these trigggers
I do operations on original table (table_orig) where I can compress the body_txt
column before making changes to database.

While insert worked just fine, update gives me error: ORA-01733: virtual column not allowed here ORA-06512: at line 13

I don't know why insert instead of trigger will not complain where as update
will complain. Is there a way around since I cannot modify application code?

Eralier I was thinging of not using views sintead use fine grained auditing
which implements "select triggers".However, I didnot find any way in FGA
to modify the value to ve returned to application (as is done in view using
decompress(...)).

Prem Received on Sun May 09 2004 - 17:09:19 CDT