We see significant difference in explain analyze Actual time in the first line of execution plan and Execution time in the last line of execution plan. What can be the reason?
It takes an hour for Postgres to gather up 7.9 BILLION (!) rows, but then it is going to take additional time to do something with all of those rows. That's where the rest of your time is going. Seeing your actual query would be a help. If this is a CTAS (Create Table As Select), then you have an hour for the 'Select' part, and the rest of your time is in the 'Create Table' part.
