Hi
Statistics are critical for performance on an Oracle DB, whatever is the application using it.
Statistics are used by the CBO to find the more efficient access path to data.
I would recommend to run statistics updates every evening through transaction DB13.
It won't have a major impact as far as statistic are updated based on a change threshold, thus it won't compute stats for all table everyday, only the one for tables that did change enough (insert/del/upd).
I'm wondering how an ISU system can behave without up to date statistics.
Watch out, with ISU huge amount of data can change daily it sound strange to not keeping statistics current but this might have been done by design, there are way to tweak statistics (like locking stats)
Ask DBA / BAsis people about some specific rules set in that area for that SAP system.
Regards
31. Last CBO statistics creation
[...]
SAP recommends that you schedule the following command at least once a week:
brconnect ... -f stats -t all