created a new discussion on upgrade.moodle.org (site to test 1.9 -> 2.0 upgrade process for moodle.org) Could create the discussion fine but got the following when deleting my post.

Debug info: Data too long for column 'action' at row 1
INSERT INTO log (time,userid,course,ip,module,cmid,action,url,info) VALUES(?,?,?,?,?,?,?,?,?)
[array (
0 => 1286107202,
1 => '1023607',
2 => '5',
3 => '220.253.204.187',
4 => 'forum',
5 => '56',
6 => 'delete discussion',
7 => 'view.php?id=56',
8 => '34',
)]
Stack trace:

• line 394 of /lib/dml/moodle_database.php: dml_write_exception thrown
• line 816 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
• line 1676 of /lib/datalib.php: call to mysqli_native_moodle_database->insert_record_raw()
• line 331 of /mod/forum/post.php: call to add_to_log()