Hi, I'm the author of the JDBC driver. I'm not sure what the problem is, but
I am going to try and talk you out of storing multi-megabytes as blobs.
Here's why....In most cases it is more overhead than it is worth. If you're
going to be serving the data from these blobs from some other type of server
(HTTP/NFS, etc), then you've more than doubled your overhead with the
over-the-wire costs. RDBMS systems are not optimized for storing and
retrieving large binary data, filesystems are.
What you probably want to do is generate some unique identifier for the file
and store it on a filesystem that the software you are writing has access
to. Use MySQL to store metadata about these files (their identifier, author,
revision history, etc), and then use standard ways of providing the file
(http/nfs/smb, etc). You will find this much more performant.
If you still want to store large files in BLOBs, I would look at increasing
your JVM heap size (by default it's around 16megs, the VM won't allocate
more memory than that), using the -Xmx switch (see your JDK documentation).
Because of the way the MySQL protocol works, the entire BLOB must be created
in memory as a single packet to be sent to the server, so the driver needs
at least the amount of memory as the size of your BLOB, plus some overhead
for escaping binary characters, plus overhead for the driver itself.
-Mark
> > We are making a project about "document manage " ,I use
> > org.gjt.mm.mysql
> > as jdbc to communicate with mysql. I can succeed in writing
> > the binary data
> > (the size about 14M) to database ,but when I write the binary
> > data that's
> > size exceed 20M I get a Exception. Please help me! Thanks!
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