class ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

def build_insert_sql(insert) # :nodoc:
  sql = +"INSERT #{insert.into} #{insert.values_list}"
  if insert.skip_duplicates?
    sql << " ON CONFLICT #{insert.conflict_target} DO NOTHING"
  elsif insert.update_duplicates?
    sql << " ON CONFLICT #{insert.conflict_target} DO UPDATE SET "
    if insert.raw_update_sql?
      sql << insert.raw_update_sql
    else
      sql << insert.touch_model_timestamps_unless { |column| "#{insert.model.quoted_table_name}.#{column} IS NOT DISTINCT FROM excluded.#{column}" }
      sql << insert.updatable_columns.map { |column| "#{column}=excluded.#{column}" }.join(",")
    end
  end
  sql << " RETURNING #{insert.returning}" if insert.returning
  sql
end