Re: random() function produces wrong range
От | Roland Roberts |
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Тема | Re: random() function produces wrong range |
Дата | |
Msg-id | m21z061igl.fsf@tycho.rlent.pnet обсуждение исходный текст |
Ответ на | random() function produces wrong range (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: [GENERAL] Re: random() function produces wrong range
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Список | pgsql-hackers |
-----BEGIN PGP SIGNED MESSAGE----- >>>>> "Thomas" == Thomas Swan <tswan@olemiss.edu> writes: Thomas> Is it possible to test (during configure phase) and then Thomas> go from there... or does it need to be the same for all Thomas> platforms? You should be able to test, but it is, of course, a statistical test. Call random() several times and test the maximum value against your thresholds of 2^15 and 2^31. If random() is generating values in the range 1:2^31-1, you would expect half of your values to be greater than 2^15-1; more importantly, if you generate, say, 10 values, you expect only a 1:1024 chance that they are all below 2^15. If those odds aren't good enough, generate more. roland - -- PGP Key ID: 66 BC 3B CD Roland B. Roberts, PhD Unix Software Solutions roberts@panix.com 76-15 113th Street, Apt 3B rbroberts@acm.org Forest Hills, NY 11375 -----BEGIN PGP SIGNATURE----- Version: 2.6.3a Charset: noconv Comment: Processed by Mailcrypt 3.5.4, an Emacs/PGP interface iQCVAwUBOYmNSeoW38lmvDvNAQHFegQAlexEvaG0t+1H0IkPWikbdMUIck1fE0DI rfcGi1M/SQ6K9Hmvi1HB/SVEU4DKGaHDoqlU7ei78OgOzchbsLL5cqAJNIsKv5QJ F4u/A0Fg7yuyRZ3/CNCo0+nTwhyDANktMw78AM5ssHCs75UxC+vHWibHHBmXJzrF 8WD2LyjPSNI= =dR25 -----END PGP SIGNATURE-----
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