Though query logging has immeasurable development value, do not use this for regular production users as the runtime logging cost is extremely high. Every log item is flushed to the disk, which in turn hurts query response. Also, note that the query log files are not created on per user or query basis, there is only one query log per OBIEE server and it would have exclusive lock on the log file, which kills concurrent performance.
On the other hand, usage tracking has a very low runtime cost and is preferred to monitor the queries being used.
