select for update returns no rows even though there is no locking thread
I'm using Ibatis library over oracle sql for my query. The select for update statement returns no rows. This happens intermittently. When this was happening last time, I executed the select statement on sqldeveloper (but without the 'for update') and got rows. This situation is not easily reproducible so I've not yet been able to ascertain whether rows are returned on sqldeveloper with the 'for update' clause. But I know for sure that there was no other thread locking the rows. How could this be happening?