Posted by Erland Sommarskog on 06/29/05 00:11

debian mojo (debian_mojo@yahoo.com) writes:
> That's true that moving away from the problem is not a solution. But
> you see that the database i'm talking about is a 24 x 7 database, and
> i'm not pretty sure how apps that are using this db.
>
> If i do pri keys to the tables, is there any possibility that the apps
> may suffer is some way.

Sure. Apps that do SELECT * on the tables and then spit out all columns
somewhere, or assume that it has a certain width will be confused by an
extra column if you add one. If you add the new column anywhere but last,
apps that refers to columns by column number will croak. All this is
bad practice, but since this site already has proven a fondness for
bad practice...

As Brian says, you need to test any changes in a safe environment. Which
includes finding out how long time it takes to add the indexes and the new
columns, so you can determine the downtime.

I should have added that beside looking for unique indexes, also look
for existing IDENTITY columns and existing guid columns, as they can
be used for the task.

> So what do you suggest? what are the other things i should take care
> of before adding the pri keys?

Read Brian's article again. There was a lot of good advice there!

--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se

Books Online for SQL Server SP3 at
http://www.microsoft.com/sql/techinfo/productdoc/2000/books.asp

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