myUSF Blackboard News

A healthy dicussion board posting

Symptoms:

A discussion board thread that has multiple replies to it may suddenly have the text of that original thread deleted and replaced with an Oracle Clob error message embedded in an HTML comment.

This will manifest itself visually in two ways

1) When viewing the discussion board, the parent thread will appear to have a empty message body. The owner, origianl post date, star ratings, everything else about the original post will be retained, but the message body is blank.

Notice the blank space where message text should normally appear

2) When editing the original discussion board thread, The body of the message when viewed with the Basic textbox editor(or with the enhanced VTBE editor in HTML source mode), you will see the following string of text

<!– Oracle does not fully support LOB manipulation (inserting or updating) using a PreparedStatement. Instead you must manipulate the LOB through the ResultSet returned by a “SELECT FOR UPDATE” query. –>

Action shot of the error message in the basic text editor

Details:

The problem occurs when two people are writing replies to the same discussion board post at the same time. When the first person submits the reply, Blackboard places a lock on the parent to update the hit count for that post. Then when the second person submits, they also attempt to put a lock on the parent post, but that fails due to the first already being present. Instead, the second reply receives an error message. The bug is that stores the error message as the body of the parent post rather than recognize that an error was thrown. When the second post gets to update finally, it also updates the parent post, setting the message body of the parent to the error message.

Workaround:

Since the original text of the parent message is deleted and replaced with the database error HTML comment, the only workarounds are to recreate the message post.

The instructor can retype the post if an instructor created it.
If settings allow, the student can also retype the post.

Blackboard is aware of the problem, and we are awaiting a hotfix.