Our experience is that the reports:expire rake task can get to where it can't finish with large numbers of reports to expire (we have 34,000 nodes and a two-hour runinterval); possibly because of this query. We were running PG 8.4; we upgraded to 9.2 and while the database itself is performing much better, we had to kill the reports:expire task after 2.5 hours because the server started swapping.

is this on 1.7? if you remove the join does it perform better? e.g.

--- a/app/models/report.rb
+++ b/app/models/report.rb
@@ -119,7 +119,7 @@ class Report < ActiveRecord::Base
     cond = "reports.created_at < \'#{(Time.now.utc - timerange).to_formatted_s(:db)}\'" 
     cond += " and reports.status = #{status}" unless status.nil?

-    Log.joins(:report).where(:report_id => Report.where(cond)).delete_all
+    Log.where(:report_id => Report.where(cond)).delete_all
     Message.where("id not IN (#{Log.select(:message_id).to_sql})").delete_all
     Source.where("id not IN (#{Log.select(:source_id).to_sql})").delete_all
     count = Report.where(cond).delete_all