In an earlier posting , Juan Carlos had mentioned about having problem with "union all"; We encountered the following after upgrading to 10gR2. Thought i will share this with the list. 1. Group by was not doing the sort in the default order where as 9.2.0.6 / 9i Rel2 was doing so 2. Same problem with SELECT DISTINCT / SELECT UNIQUE 3. And Recently SELECT name, SUM(basic) total FROM TEST WHERE basic=20 GROUP BY name ORDER BY 2 DESC did not work; If you use SELECT name, SUM(basic) total FROM TEST WHERE basic BETWEEN 20 AND 20 GROUP BY name ORDER BY 2 DESC then it works!!! Patch number is 5415881. Please double confirm with your db release by writing simple SQL queries prior to proceeding. Some of our reports / queries were producing "different" results after move to 10gRel2. Also check your UNION/UNIONALL queries. HTH GovindanK Certified DBA Learning Stops at ... Infinity