If you are seeing LOG messages related to the statistics as below it represents the IO load on the machine
where the database is running.
LOG: using stale statistics instead of current ones because stats collector is not responding
The stats collector needs to gather the information frequently and during the high load it may
lead to the above messages. To overcome this issue we suggest to mount the "stats_temp_directory"
on a RAM based file system.
Those are the temporary stats and hence it is fine to use the RAM based file system.
Note: Changing this parameter ONLY requires reload of the database server which doesn't impact the