Hi, i'm working in db2. I've to tune the below query.

Select a.run_dates_stations_id, a.station_master_id, a.run_dates_id,b.call_letters, b.dma_id
from contract.run_dates_stations a left outer join customer.station_master b
on a.station_master_id=b.station_master_id
where (a.ibmsnap_logmarker= '1900-01-01 11:16:30.0' or b.ibmsnap_logmarker= '1900-01-01 11:16:30.0')

when i searched for access plan & optimized query in db2 command center,
i found the below optimized query.

Select q3.$c4 as "run_dates_stations_id", q3.$c6 as "station_master_id", q3.$c3 as "run_dates_id", q3.$c1 as "call_letters", q3.$c0 as "dma_id"
from (select q2.dma_id, q2.call_letters, q2.ibmsnap_logmarker, q1.run_dates_id, q1.run_dates_stations_id, q1.ibmsnap_logmarker, q1.station_master_id
from contract.run_dates_stations as q1 left outer join customer.station_master as q2 on (q1.station_master_id = q2.station_master_id)) as q3
where ((q3.$c5 = '1900-01-01-11.16.30.000000') or (q3.$c2 = '1900-01-01-11.16.30.000000'))

the query is not working and giving an error q3.$c5, q3.$c2 are not valid.
Both should refer to ibmsnap_logmarker field for the two tables.
Can anyone suggest/improve the query?