Oracle-L: PK field - number of char

From: Mercadante, Thomas F <NDATFM_at_labor.state.ny.us>
Date: Wed, 17 Apr 2002 10:52:02 -0800
Message-ID: <F001.00446FA8.20020417105202@fatcity.com>

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: Grabowy, Chris
INET: cgrabowy_at_fcg.com

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Author: Pardee, Roy E
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