Joseph,
Again, I will preface my statements with the recommendation that you
do a simple test to confirm your design. One of the really cool
aspects of Cayenne is that your workflow for a modification (or test
in this case) is streamlined by CayenneModeler.
On Mar 21, 2009, at 6:41 PM, Joseph Schmidt wrote:
My preference (and it seems to be fairly efficient), is to continue
with the standard design pattern of storing metadata (file-path,
etc) in the database and storing the file in the filesystem. You
can them make programatic references much easier.
Thank you. I used too mostly this is the approach with other
frameworks.
I just wondered if Cayenne has some better support for this common
scenario.
I don't want to speak for the designers, but I suspect that their
designs are in some respects limited to ORM patterns that can be
abstracted across the leading databases.
As I mentioned, from my testing, Cayenne appears to perform
competently wrt BLOB's (I think any limitations are DBMS-config like
size limit and such). The problem, is downstream of Cayenne. I
Googled the issue and here is a JSP example
http://fdegrelle.over-blog.com/article-992927.html
My analysis is that you can make it work, it is just going to result
is way-ugly code (i.e. annoying maintenance-overhead for the life of
your webapp).
The second one seems to be the most efficient, but than the entire
transaction support is lost :(.
Not sure what you mean by "transaction support", so I can't comment
on this.
I mean that in the case of a file system based approach, where the
metadata is in the database, the operations on files are not guarded
by transactions, nor can they be process in the same Cayenne
transaction like on the metadata of those files. So when problems
occur during
editing, deleting, etc. the system is not consistent and can't be
really rollbacked.
I see. I believe that the maintenance advantage still out-weighs the
rollback issue. As a work-around, you could always implement a "Trash
Can" - like design pattern and initiate a rollback if you do a Cayenne-
rollback. (Just a thought.)
Joe
