Quote Originally Posted by LKBrwn_DBA View Post
Seems you are missing indexes and/or statistics (on indexes also)....
Check if the indexes on 9i are the same as on 10g in number and columns indexed.
The number of indexes is the same (for this schema) on 9i and 10g.
The indexes all have statistics (as do the tables).

While the above would explain slower performance (even though this is not the case) what would explain the sudden complaint about GROUP BY clause. Note that it is not enough for it to fall over but it is grumbling about it while executing the query. With the Enterprise manager console thick client thingy, if you look at the details of the session it is still processing but if you click on the SQL tab it says a database error has occured
'ORA-00979 not a GROUP BY expression'.

Annoyingly this is one report our users didn't test and of course this is the one that is not working.