| From: | David Garamond <lists(at)zara(dot)6(dot)isreserved(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | "D(dot) Dante Lorenso" <dante(at)lorenso(dot)com>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Drawbacks of using BYTEA for PK? |
| Date: | 2004-01-12 15:52:49 |
| Message-ID: | 4002C2D1.7020202@zara.6.isreserved.com |
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| Lists: | pgsql-general |
Tom Lane wrote:
> David Garamond <lists(at)zara(dot)6(dot)isreserved(dot)com> writes:
>
>>Perhaps I can make a GUID by MD5( two random numbers || a timestamp || a
>>unique seed like MD5 of '/sbin/ifconfig' output)...
>
> Adding an MD5 hash contributes *absolutely zero*, except waste of space,
> to any attempt to make a GUID. The hash will add no uniqueness that was
> not there before.
Of course, in the above case, MD5 is used to compress the "uniqueness"
(which should be more than 128-bit, comprised of: a) [good] random
number; b) timestamp; c) a "node ID" element, either from /sbin/config
output which contain MAC address, or from the hash of harddisk content,
etc) into a 128-bit space.
--
dave
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