The following bug has been logged online:
Bug reference: 1107
Logged by: Jozef Behran
Email address: jozef.behran@krs.sk
PostgreSQL version: 7.3.2
Operating system: Mandrake GNU/Linux
Description: Missing feature: interval <-> numeric quantity
conversion
Details:
Having two timestamps it is common need to know how many
seconds/minutes/hours/days/etc. passed from one to the other. However there
is no easy way to do this task.
The basic idea is subtracting the two timestamps. However it gives a data
type called "interval". The thing I would like to have is a function that
takes the "interval" and outputs it's length. Currently when I want a
program to know how long an interval is I must let it parse the interval
textual representation (which may be subject to change) to obtain what I
want.
I consider this to be a bug, because it seriously degrades the usability of
timestamp data types in applications where interval lengths are extensively
demanded and used. I was forced to store these data in an INT8 data type
column because my project extensively uses time interval lengths for other
computations and converting dates to INT8 before write and then subtracting
the numbers when need arises is MUCH faster than subtracting timestamps and
parsing the result of such a subtraction.
Note: The 'date' data type does not have this problem. The result of two
dates subtraction is an integer (not 'interval') which I can use quite
easily.