PostgreSQL Get a random datetime/timestamp between two datetime/timestamp

You can do almost everything with the date/time operators:

select timestamp '2014-01-10 20:00:00' +       random() * (timestamp '2014-01-20 20:00:00' -                   timestamp '2014-01-10 10:00:00')

I adapted @pozs answer, since I didn't have timestamps to go off of.

90 days is the time window you want and the 30 days is how far out to push the time window. This is helpful when running it via a job instead of at a set time.

select NOW() + (random() * (NOW()+'90 days' - NOW())) + '30 days';

You could build the timestamp from a random integer (unix stamp), e.g.:

select timestamp 'epoch' + (          extract('epoch' from timestamp '2014-10-01 10:00:00')        + random() * (                     extract('epoch' from timestamp '2014-20-01 20:00:00')                   - extract('epoch' from timestamp '2014-10-01 10:00:00')       )) * interval '1 second'

Wrap it in an SQL function if you use it often, as it's not very readable even after attempting to format it somewhat.

Another way to do it would be to use generate_series() from the start date to the end date, ordered by random(), but that would make things very slow with larger date intervals so you'll be better off with the above approach.