Need to change the table with timestamp to unix epoch time for RISING column in DB Connect

[jugalkinariwala]

I need to ingest the data from DB to Splunk via DBCONNECT.

Need to choose a column for a RISING column which has a data and time field in it with below format :

starttime=2020-06-16 01:26:35.595026665

How shall I convert the above time format at the query level so that it is used for checkpoint as a primary key to use it as a RISING Column .

[jugalkinariwala]

If the table generates 1000 rows every 10mins

And if I am using Batch mode 

So shall I opt for DESC or ASC to retrieve the last rows that are generated from the table ?