Subject Re: One blob for many records.
Author Ann W. Harrison
At 02:56 PM 3/29/2001 +0500, Dimitry Sibiryakov wrote:

> ... It's impossible to have two or more
>records referring to one blob, isn't it? Why? If I have an useful large
>picture, why have i to keep in the database two or more copies of it? I
>think it would be better to keep the counter of references to blob and
>remove it only when the counter reaches zero.

I'm replying both to this list and to the IB-Architect list at,
because your idea is interesting and deserves some discussion. My inclination
is to suggest that you create a table of blobs and link to that table, keeping
a reference count with triggers. In short, I would push the problem up from
the engine to the application. My reason is that different applications would
expect different behavior from update and delete. In many cases, but not all,
an update would create a new blob, linked only to the updater. In many cases,
a delete should decrement the reference count and not remove the blob
unless the
count goes to zero. On the other hand, a shared document should reflect
to all tables linked to it.

Does any one have experience with systems that behave like this? Comments?


We have answers.