gistfile1.txt

def non_multi_dupes
  non_multi_specs = Spec.find_all_by_is_multival(false).select{|x| parent = x.try(:parent); !parent.try(:is_multival)}
  non_multi_sids = non_multi_specs.collect {|s| s.id}
  
  # this sql will find all spec values grouped by product_id+spec_id where the count of this grouping is greater than 1
  sql = ["select * from spec_values where spec_id in (?) group by spec_id, product_id having (count(*) > 1)", non_multi_sids]
  
  puts "about to do a beefy sql statement.  Shouldn't take longer than 10 seconds or so."
  single_dupe_svs = SpecValue.find_by_sql(sql)
  
  result = []
  
  # since the grouping done by the sql statement has squished all duplicates, 
  # we need to re-find the one surviving duplicate's brothers
  single_dupe_svs.each do |sv|
    result << [sv.product_id, SpecValue.find_all_by_product_id_and_spec_id(sv.product_id, sv.spec_id)]
  end
  
  result
end