Hi Niall, Aside from running the awrsqlrpt. For this I would be using SQLTXPLAIN for the two SQL statements and use the "compare" facility. *Database Community: SQLTXPLAIN 2: Comparing Two Explain Plans using the SQLTXPLAIN COMPARE method [ID 953964.1]* * * *The output is very comprehensive and you'll see the highlighted parts in red as the differences. From there you can do drill down on the CBO, objects, configuration, and others.. * * * * * * * * * *- Karl Arao* *karlarao.wordpress.com *