Outer joins ?
Stupid question but did you check if update statistics was done under same conditions in both versions ?What does sqlexplain say on both versions ?What does sqltrace say ?Abraço
You will have checked but ... are the sqexplains identical ?
Presumably the upgrade was on the same machine.O/S?
DIRECT_IO in use or not? Was it before? Number of CPU VPs if in use? Number of AIO VPs if not in use?"OUTERS" will always read more than other queries (well, sort of ... cartesian joins will do loads of reads :) )
VMs in the mix somewhere ?
If you can repo with small datasets then I would agree with Art and blame HCL J