Arthur Blake wrote:
Yes, that was the problem.
If I change my code to keep the Connection open after I have a Blob in
hand, and then read the Blob it works.
It appears that also the ResultSet and PreparedStatement I used to fetch
the Blob must also remain open until I'm done reading the Blob.
Generally, you should be able to close result sets and statements and
still be able to access the Blob. However, if you run with autocommit
on (default), closing a result set may commit the transaction, and Blobs
may not be accessed after the transaction has been committed.
That seems reasonable.
Sorry that I didn't see that in the release notes (they are quite big)
as I didn't even realize I was doing this in the code... (my Lob reading
code was buried in some utility classes.)
I believe the Release note entry for this is DERBY-2729 .
Paraphrasing: "Now Blobs and Clobs store their data in temporary files..."
Can I assume that Blob reads (especially for smaller Blobs) will be
slower now because they will have to be copied to temp files?
The temporary files will only be created if you use the JDBC Blob
methods to change the content of a blob (e.g., setBytes). For the
embedded driver, these methods were added in 10.3. For methods existing
in 10.2, I do not think the performance has changed much. (For the
client driver, we have switched to a locator-based inmplementation and
some operations should be much faster, while a few will be probably be
slightly slower.)
--
Øystein
