0 - 2 of 2 tags for timezone change

Hi All,
 
I have a scenario here as below
 
TAB1 has 100Bn rows with timestamp(RPTG_TS) in 'America Pacific' and need to convert this timestamp column to GMT timestamp.

Hi Guys,
i have come up with a situation where the data comes from different server and now i want to get them all in Common TIMESZONE - i.e AEST (Australia Eastern) , so Help me in Identifying what all Settings in DBS needs to be changed for the Same?
Thanks in Advance.