Re: Enforce primary key on every table during dev?

On 03/01/2018 02:09 PM, Daevor The Devoted wrote:
>
>
> On Thu, Mar 1, 2018 at 9:00 PM, Ron Johnson <ron(dot)l(dot)johnson(at)cox(dot)net
> <mailto:ron(dot)l(dot)johnson(at)cox(dot)net>> wrote:
>
> On 03/01/2018 12:32 PM, Daevor The Devoted wrote:
>>
>>
>> On Thu, Mar 1, 2018 at 8:18 PM, Ron Johnson <ron(dot)l(dot)johnson(at)cox(dot)net
>> <mailto:ron(dot)l(dot)johnson(at)cox(dot)net>> wrote:
>>
>>
>> On 03/01/2018 11:47 AM, Daevor The Devoted wrote:
>>>
>>> On Thu, Mar 1, 2018 at 2:07 PM, Rakesh Kumar
>>> <rakeshkumar464(at)aol(dot)com <mailto:rakeshkumar464(at)aol(dot)com>> wrote:
>>>
>>>
>>> >Adding a surrogate key to such a table just adds overhead,
>>> although that could be useful
>>> >in case specific rows need updating or deleting without
>>> also modifying the other rows with
>>> >that same data - normally, only insertions and selections
>>> happen on such tables though,
>>> >and updates or deletes are absolutely forbidden -
>>> corrections happen by inserting rows with
>>> >an opposite transaction.
>>>
>>> I routinely add surrogate keys like serial col to a table
>>> already having a nice candidate keys
>>> to make it easy to join tables.  SQL starts looking ungainly
>>> when you have a 3 col primary
>>> key and need to join it with child tables.
>>>
>>>
>>> I was always of the opinion that a mandatory surrogate key (as
>>> you describe) is good practice.
>>> Sure there may be a unique key according to business logic
>>> (which may be consist of those "ungainly" multiple columns), but
>>> guess what, business logic changes, and then you're screwed!
>>
>> And so you drop the existing index and build a new one.  I've
>> done it before, and I'll do it again.
>>
>>> So using a primary key whose sole purpose is to be a primary key
>>> makes perfect sense to me.
>>
>> I can't stand synthetic keys.  By their very nature, they're so
>> purposelessly arbitrary, and allow you to insert garbage into the
>> table.
>>
>>
>> Could you perhaps elaborate on how a surrogate key allows one to
>> insert garbage into the table? I'm afraid I don't quite get what
>> you're saying.
>
> If your only unique index is a synthetic key, then you can insert the
> same "business data" multiple times with different synthetic keys.
>
>
> --
> Angular momentum makes the world go 'round.
>
>
>
> That might be where we're talking past each other: I do not advocate for
> the arbitrary primary key being the only unique index. Absolutely not.
> Whatever the business rules say is unique must also have unique indexes.
> If it's a business constraint on the data, it must be enforced in the DB
> (at least, that's how I try to do things).

Why have the overhead of a second unique index?  If it's "ease of joins",
then I agree with Francisco Olarte and use the business logic keys in your
joins even though it's a bit of extra work.

--
Angular momentum makes the world go 'round.