Re: win32 random number generator
Tom Lane <[email protected]> Mon, 22 Aug 2005 16:47:46 -0400
| Newsgroups | gmane.comp.db.postgresql.devel.win32 |
|---|---|
| Message-ID | <[email protected]> |
"Merlin Moncure" <[email protected]> writes: > The windows random number of generator (a port of lrand48 in random.c) > seems a little weak. It seems to only offer about 16 bits of precision. > Maybe there is a bug in the implementation? > esp=# select count(*) from (select distinct random() from > generate_series(1,1000000)) q; > count > ------- > 65559 > (1 row) That's pretty awful, all right. I get numbers like this on two different Unix machines: regression=# select count(*) from (select distinct random() from generate_series(1,1000000)) q; count -------- 999769 (1 row) postgres=# select count(*) from (select distinct random() from postgres(# generate_series(1,1000000)) q; count -------- 999787 (1 row) Anyone care to burrow into the code and see what its problem is? regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org