The other approaches of fixing the estimates, cost params, etc are the right way of fixing it. *However* if you needed a quick fix for just this report and can't find a way of setting it in Jaspersoft for just the report (I don't think it will let you run multiple sql statements by default, maybe not at all) there are still a couple more options. You can define a new datasource in jasper, point this report to that datasource, and have that new datasource configured to not use the nested loops. You could do that either by making the new datasource use a different user than everything else, and disable nested loops for that user in postgres, or you could probably have the datasource initialization process disable nested loops.
