Hi, I have a view in which I want to randomly assign values if certain conditions hold. I was getting surprising results. Here is a (very) simplified version of the view, which seems to indicate the problem: CREATE OR REPLACE VIEW test_view AS SELECT CASE WHEN random() < .3333 THEN '1' WHEN random() < .3333 THEN '2' ELSE '3' END AS test_value FROM client ; It seems this should generate a random number between 0 and 1, and set test_value to '1' if this first generated number is less than .3333. Otherwise, it should generate another random number, and set test_value to '2' if this is less than .3333. And if neither of the random numbers are less than .3333, it should set test_value to '3'. It seems to me that there should be a relative even distribution of the 3 values. However when I run this, the values are always similar to what is below: X_test=> select test_value, count(*) from test_view group by 1 order by 1; test_value | count ------------+------- 1 | 23947 2 | 16061 3 | 32443 Why are there significantly fewer 2s? I understand that random() is not truly random, and that the seed affects this value. But it still confuses me that, no matter how many times I run this, there are always so few 2s. If it is generating an independent random number in the second call to random(), then I don't know why there are more so many more 1s than 2s. Thanks! -jessi -- Jessi Berkelhammer Downtown Emergency Service Center Computer Programming Specialist -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
