Need help in transferring FP to Int64 DateTime

Hi All,

I am sure this question has been asked before, however, I failed to find any related topics in the internet. We have a database about 100GB in size. It was started back in 7.x days and has been upgraded along the way to 9.0. Because of the historical reason, all timestamps are stored in FloatingPoint. To use pg9, we had to compile it with FP support instead of the default Int64. Some recent research shows that PG team will eventually dump FP support in favor of int64 in future, we figured we need to make the move to Int64 before the database gets even larger. The challenge we now face is how to "convert" the database fast enough, so that required down time is minimized. Searching through the internet for 2 days yields little fruit so far... Can someone please provide enlighten us?

Cheers,