Jack, I had an advantage - I knew what I was looking for before I got the trace file. There aren't many applications around that make use of clusters, so their implementation is not well known. Regards Jonathan Lewis ________________________________ From: jack.van.zanen@xxxxxxxxx [jack.van.zanen@xxxxxxxxx] on behalf of Jack van Zanen [jack@xxxxxxxxxxxx] Sent: 06 November 2013 21:16 To: Jonathan Lewis Cc: oracle-l@xxxxxxxxxxxxx Subject: Re: Misbehaving select Hi Jonathan, As oracle support is still trying to point us to optimizer stuffing up, this is going to be a great help to speed things along with oracle support. They have been sitting on the same block trace without anything sofar. Thanks Jack van Zanen