Re: SQL design pattern for a delta trigger?

On Dec 10, 2007, at 5:04 PM, Colin Wetherbee wrote:

> For what it's worth, the real algorithm would be as follows.  I  
> hadn't had enough coffee yet, and I forgot the UPDATE bit.
>
> IF
>  (a query matching your old data returns rows)
> THEN
>  UPDATE with your new data
> ELSE
>  INSERT your new data

Still exists race condition.  Your race comes from testing existence,  
then creating/modifying data afterwards.  You need to make the test/ 
set atomic else you have race.