The file: src/database/upgrade/9/gateway_oracle.sql contains invalid SQL. Oracle (at least version 10g which is what we use) disallows a modify of a BLOB column type to CLOB.
You will have to create a new table, copy the data over, and drop the old table.
Would you be willing to create a patch for the script with your proposed change? You should be able to attach that patch to your post.
After reviewing our logs, it would seem that the gateway plugin was completely unable to insert into the BLOB columns anyway. This mitigates the need for a conversion script, making things much simpler. Attached is a script for re-creating the tables.
update9_oracle.sql (620 Bytes)