Re: OO versus RDB
Date: Wed, 28 Jun 2006 15:19:27 GMT
Message-ID: <36xog.1576$%67.367_at_trndny02>
Responding to Marshall...
>>>A schema change breaks a query or it doesn't.
>>>If it doesn't all is well.
>>>If it does you'll have to investigate the code
>>>dependent on the query.
>>
>>It breaks the query, but not the problem solution that needs the data.
>
>
> This sounds sensible, but isn't. Any schema-change breakage
> will affect both query and code. If a queried column is deleted,
> the query will need changing, but also the code has to reconsider
> what it will do in the absence of the column.
I'm afraid that is not true. Consider
[SalariedEmployee]
* employeeNo
+ salary
...
This sort of situation is actually rather common at the enterprise level. That's because different applications use the same data for different reasons. When requirements changes trigger changes to the schema, those requirements typically only affect some of the reasons the applications use the data. So only a fraction of the applications that use the data are affected by the change and have to be modified for the requirements changes. For the rest of the applications the requirements changes simply aren't relevant so the change to the schema should be transparent to those applications.
There is nothing wrong with me that could not be cured by a capful of Drano.
H. S. Lahman
hsl_at_pathfindermda.com
Pathfinder Solutions -- Put MDA to Work
http://www.pathfindermda.com
blog: http://pathfinderpeople.blogs.com/hslahman
Pathfinder is hiring:
http://www.pathfindermda.com/about_us/careers_pos3.php.
(888)OOA-PATH
Received on Wed Jun 28 2006 - 17:19:27 CEST