On Tue, May 4, 2010 at 3:16 PM, Merlin Moncure <mmoncure@gmail.com> wrote:
> On Tue, May 4, 2010 at 9:40 AM, Merlin Moncure <mmoncure@gmail.com> wrote:
>> On Sat, May 1, 2010 at 4:14 PM, John R Pierce <pierce@hogranch.com> wrote:
>>>
>>> If your 'natural key' is a large text field, I'd have to assume there's some
>>> point at which a surrogate index would be more efficient. Would this be
>>> above a few dozen characters, or a few 100 characters? I wouldn't want a
>>> PK based on a multi-K byte text field for a table that has many 10s or 100s
>>> of 1000s of rows, for sure.
>
> one more note about this. if you truly have a situation where a multi
> kilobyte chunk of data is the key, you can always digest it and use
> that. you lose the natural ordering -- but in these type of cases it
> usually doesn't matter.
>
99% of all cases, where I introduced bigint surrogate key, in tables
that hold account, customers, and that sort of bollocks, were straight
wins, sometimes measuring 3-4x.
Another thing, If your PK changes, it is no longer a PK, you can't rely on it.
--
GJ
