Deleting a list of external xinv/xinx files using JDBC

I'm using the JDBC setBytes to insert a list of large object blobs.
The side-effect of this is two external files (xinvOID and xinxOID)
for every blob inserted.

If I use a JDBC delete sql statement to delete the records
containing the blobs, the external xin* files are not deleted.

Is this by design? If so, is there a work around for deleting
a LIST of records AND the associated external blob file?


Foe example:
CREATE TABLE "some_blobs" (
"blob_id" int4 PRIMARY KEY,
"the_blob" oid NOT NULL
);

JDBC insert statement for adding blob records:
insert into some_blobs (blob_id, the_blob) values (?,?)

JDBC delete statement for removing all blob records:
delete from some_blobs

Thanks
Xavier