I am writting such float value from Python (6.481044303797468) converted to string via StringIO '6.481044303797468' into Postgresql column of type NUMERIC(13,8). I read it back into Python which is returned as Decimal('6.48104430').
Why the precision is smaller?
You asekd to remember just 8 digits after decimal point in here
NUMERIC(13,8) change type for what your precision is desired
Python writes float to Postgresql but it is precision is lesser