Bruno Wolff III wrote:
On Wed, Aug 27, 2003 at 00:09:34 +0200,As the newbe I am, I don't understand much abaut serialized isolation, db-locks and so on.
Andreas Fromm <[EMAIL PROTECTED]> wrote:
Bruno Wolff III wrote:
This is what I want to do, but my question is how can I easely now if there is someone referencing a certain record. Is it just possible by searching every table that could reference it or is there an other way of doing it without adding an reference count column?On Tue, Aug 26, 2003 at 18:34:04 +0100, Richard Huxton <[EMAIL PROTECTED]> wrote:
I don't think that is what he wants. He seems to want to go in the other direction. That is going to require custom triggers and probably adding a reference count column to data-tables.
You can use a reference count in the row you are interested in. You would need to create triggers on all referncing tables to update the reference count as necessary. Also as pointed out previously, you want to use serialized isolation (and handle retries) or exclusively lock the table (and worry about deadlocks and a concurrency bottleneck) if you use this approach.
You could do a scan of all possible referencing tables whenever you update
any of the referencing tables. However, this approach has pretty much the
same problems as using a refernce count and will probably be slower.
Do I need to care abaut all these considerng that the database will only be accessed by one user at a time, and the hole db will not have many entries?
Are there basic dessign considerations that should be taken, or is it something that can be added in the future?
As I don't have much time to invest in this project, I will have to come up with some other solution. Maybe something like a 'garbage collection' routine, that runs over the db from time to time and delets all unreferenced records.
-- Andreas Fromm
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