RE: PK field - number of char

Jared,

I disagree. In some cases, I would support and use natural values for Primary keys.

In the case of State Codes, County Codes, Yes/No codes and other that are too obvious, I really do not see the value of using an sequence number for the PK.

I have a YES/NO table in my database. The Web developers use a drop-down field to allow the users to select the value they want (YES or NO). If the developers were required to to support the sequence number, it makes the coding a tiny bit more complicated (obviously, you and I can think of dozens of ways to make it insignificant).

I guess I'm thinking that this is one of those personal preference things. My original question was looking for a good reason why I should NOT use chars in an index (thus forcing me to always use a sequence as the PK). So far, I see no reason not to .

See ya.

Tom Mercadante
Oracle Certified Professional

-----Original Message-----
Sent: Thursday, April 18, 2002 10:27 AM
To: ORACLE-L_at_fatcity.com; Mercadante, Thomas F

Tom,

If you are generating keys as you should be, they will be numeric.

Jared

On Wednesday 17 April 2002 11:52, Mercadante, Thomas F wrote:
> All,
>
> Does anyone have any specific metrics demonstrating that a PK that is
based
> on a number field is faster than a PK based on a character field?
>
> I've seen it mentioned a couple of times today under the "Design Question"
> topic.
>
> It doesn't make any sense to me that one or the other would be faster.
> After all, we are talking about comparison searches within the B-Tree
index
> structure. Why searching down the tree for a number is any faster than a
> char is lost on me.
>
> Just curious if anyone has a reference someplace pointing this out.
>
> Thanks
>
> Tom Mercadante
> Oracle Certified (Stupified today) Professional
>
>
> -----Original Message-----
> Sent: Wednesday, April 17, 2002 2:21 PM
> To: Multiple recipients of list ORACLE-L
>
>
> If you go with the first option, you will likely be able to get out of
> joining your STATE table to the referencing tables in a bunch of cases
> (since the 2-letter abbreviation is interpretable on its own). But if
> you'll wind up having to do the join anyway (e.g., to display the
> STATE_DESC) then those joins will likely be faster on a numeric...
>
> HTH,
>
> -Roy
>
> Roy Pardee
> Programmer/Analyst
> SWFPAC Lockheed Martin IT
> Extension 8487
>
> -----Original Message-----
> Sent: Wednesday, April 17, 2002 10:19 AM
> To: Multiple recipients of list ORACLE-L
>
>
> To simplify my question, if I am creating a STATE table to hold all the
> states of the US, should I create it like this...
>
> Name Null? Type
> ----------------------------------------- --------
> ----------------------------
> STATE_CODE NOT NULL CHAR(2) <-- PK
>
> STATE_DESC NOT NULL VARCHAR2(50)
>
> or like this...
>
> Name Null? Type
> ----------------------------------------- --------
> ----------------------------
> STATE_ID NOT NULL NUMBER <-- PK
> STATE_CODE NOT NULL CHAR(2)
> STATE_DESC NOT NULL VARCHAR2(50)
>
> I'm trying to figure out which is more efficient, STATE_CODE or STATE_ID,
> when doing a PK lookup, dealing with FKs, etc.
>
> Many TIA!!!
>
> Chris

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Author: Mercadante, Thomas F
  INET: NDATFM_at_labor.state.ny.us

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