> I'm pretty
> sure this won't work for some db's. I know it won't work in
> Oracle due
> to their JDBC drivers. Here's a summary of my discoveries:
>
> 1) I was under the impression that I could just use my own Clob
> implementation and call PreparedStatement.setClob.
> Unfortunately, this
> is not the case. Oracle JDBC will throw a ClassCastException if it
> doesn't get an oracle.sql.CLOB. Furthermore, to save a CLOB for the
> first time, the row needs to be created first, then you need
> to select
> the Clob object, and then finally you can write the data out
> to the db.
> This means that CLOB support is not going to be as simple as
> providing a
> ClobType.
Yes, I already discovered this! (Oracle is the only sticking point
with this approach, btw. Other drivers don't mind. But you didn't
read my post properly. This is NOT how I am going to do it! The
object passed to ClobType only implements Clob from the purposes
of being useable in the persistent class. ClobType actually looks at
it, figures out its a wrapper and calls setString().
> 2) In order to write to a Clob, it must first be retrieved
> with a SELECT
> .... FOR UPDATE statement, which means that we'd have to fool
> around with
> locking when writing Clobs.
I havn't noticed this myself. In fact my tests havn't shown
this to be a problem. Anyway, it is already possible to do
select for update in Hibernate, by using LockMode.UPGRADE.
We might have to extend that functionality just a little bit,
if it turns out that you are correct. But this is certainly
not insurmountable.
> Something else just occurred to me: supporting Clobs and
> Blobs in long
> transactions will get pretty tricky.
Make that "virtually impossible". There will be many
restrictions upon how you can use objects with Blob or
Clob properties.
> P/S - If you haven't already written your own ClobImpl, I can
> send you
> what I have as a starting point.
Yes please! I had something *really* simple but threw it away
after initially testing its feasibility.
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