It is hard to overstate the importance of Oracle statistics to performance and stability of Windchill systems. Having correct and accurate statistics is something which is handled by Oracle by default and ideally isn't something that needs be even thought about by Windchill Administrators or DBA's. But like any other complex piece of software the devil is in the details. The two white papers below recently came to my attention, I learned a couple of things and would encourage anyone interested in Oracle performance tuning to also go through them too.
Oracle statistics white papers:
http://www.oracle.com/ocom/groups/public/@otn/documents/webcontent/1354477.pdf
http://www.oracle.com/technetwork/database/focus-areas/bi-datawarehousing/twp-bp-optimizer-stats-04042012-1577139.pdf
