Database Design Advice
david at cantrell.org.uk
Fri Nov 8 19:33:11 GMT 2013
On 08/11/2013 18:08, James Laver wrote:
> On Fri, Nov 8, 2013 at 5:22 PM, Yitzchak Scott-Thoennes
> <sthoenna at gmail.com> wrote:
>> On Fri, Nov 8, 2013 at 12:38 AM, Mark Stringer <mark at repixl.com> wrote:
>>> I'd guess that the date_created is being stored in the table, so could be
>>> used to order the records without the need for a serial, if ordering is the
>>> only concern.
>> Never use date/times as unique identifiers/sort keys.
> I'll agree with the former, but what's the reasoning behind the latter?
Because you might need to know which of two events at
2013-11-08Z19:31:04 happened first. Sure you could use microseconds or
whatever to get better resolution, but all that does is make the problem
less likely, it doesn't make it go away. You also normally want sort
order to be consistent. If you have two records where the sort field is
the same, the order they come out is going to be unpredictable.
David Cantrell | Bourgeois reactionary pig
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