Re: what is wrong with this idea ...

• Gurelei <gurelei_at_yahoo.com>

> Hi. We have a table in our data warehouse which keeps
> info about calls made. This table has a child table
> with some detailed information about parts of the
> call. There may be any number of "parts" within a call
> (1 to many) and every part has a status.
>
> MY developer wants to add a string field to the parent
> table which will concatinate all the statuses for
> all the parts within this call. For example if
> a call has 4 parts and their statuses are "A","B","A"
> and "F", the value of that field will be "ABFA". Then
> the developer will be able to query smalle parent
> table instead of a large child table in order to see
> how many calls had at least one part with status "A"
> or statuses "A" and "F" etc by using a INSTR (or
> SUBSTR) command.
>
> Would it be better (from performance/CPU standpoint)
> to add several separate fields: STATUS_A_CNT,
> STATUS_B_CNT (the list of status codes is fairly
> static) instead? There is something about this string
> that rubs me the wrong way, but I can't put my finger
> on it.

I would avoid composite fields at all costs. Performance is one reason: you have to perform a substr to get at the foreign key value. Function indexes can help there but properly normalizing the data will do a better job.

--
Steven Lembark                               2930 W. Palmer
Workhorse Computing                       Chicago, IL 60647
                                            +1 800 762 1582
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Author: Steven Lembark
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