Re: [Wonder-disc] [OT]Re: Question about ERPrototypes

[Chuck H. <ch...@gl...>]

On Jul 3, 2008, at 3:13 PM, Philippe Rabier wrote:

>
> On 3 juil. 08, at 22:37, Guido Neitzer wrote:
>
>> On 03.07.2008, at 13:10, Philippe Rabier wrote:
>>
>>> It makes sense. However, I avoid to u
>>> se inheritance as explained Max
>>> Mueller in 2005 (very interesting session).
>>
>> I haven't seen that session. What are the reasons?
> After verification, it was Ravi Mendis. What he said:
> - minimize inheritance

Note that he did not say eliminate.  Comparing the mess of code that  
results from not using inheritance, it would take a pretty pressing  
performance problem to get me to drop inheritance.


> - in case of inheritance, always inherit from an abstract entity

Often good advice but I don't know that I would say "always".


> - avoid inheritance greater than 1 level

I am not clear on what that would avoid.


> For example, the muzicStore has more than 400 entities but only 5% are
> inherited entities
>
> All this advices was given for avoiding performances issues.


If you are using single table inheritance, there is not much in the  
way of performance issues.  5% inheritance in an average model is  
probably in the "normal" range of things.  Maybe on the low side, but  
not very unusual.

Chuck

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