Hi,

Seems to me that I found the place where it happens, but I do not
know why this happens. When we get XSQLVAR structure from server it
contains a mark that the fild is not null, but the ID of the blob is
null.

In org.firebirdsql.jdbc.FBBlobField, method Blob getBlob(int) I made
a bug:

if (blobId == null)
blobId = new Long(0);

Unfortunatelly I do not have time to make more thorough investigation
of this issue. I would be very grateful if you replace this code with

if (blobId == null)
return BLOB_NULL_VALUE;

and report results here. This might be a bug, or there might be a bug
in GDS_Impl.java where the XSQLVAR is retrieved.

I do not commit this code to CVS because I'm not sure if this is
correct fix or not. Please make some testing.

Best regards,
Roman Rokytskyy