Full table scan on query using primary key?

[slimdave]

Your query will ful scan the uln_syn table and test the EXISTS condition for each row. Try this instead:

SELECT uln_syn.poe_ald_cal AS grp0, SUM ( uln_syn.sumoftotal_stons ) tot0
    FROM uln_syn
   WHERE tpfdd_runid_uln = (
            SELECT ca_keys.comp_key
              FROM ca_keys
             WHERE ca_keys.comp_id = '0x080e00000107235e9e7f0a1428098124')
  GROUP BY uln_syn.poe_ald_cal;