show create table transferdata;

show create table units_unitgroups;

show index in transferdata;

show index in units_unitgroups;

analyze select *

from

  (select distinct td.id,

    td.name,

    td.data_type,

    td.data_size,

    td.created_new,

    td.owner_id,

    td.digest,

    td.trainclass,

    td.unit,

    td.instance

  from transferdata td,

    units_unitgroups uu

  where td.trainclass     = uu.fk_trainclass

  and td.unit       = uu.fk_unit_number

  and td.data_type_new   = 19

  and td.created_new     >= 1490006800000

  and td.trainclass     = 'myclass'

  and uu.fk_unitgroup_id in (1)

  order by created_new

  ) as subquery

  limit 500;