Re: [Mogwai-users] Attribute order

[Boyd, C. <cr...@my...>]

Phinux,

Are you just wanting to change the attribute order in the UI and not the 
DBMS?  Or both?

In the data modeling world there are three concepts of attribute order: 
There is the Logical Data Model side, the Physical Data Model side, and 
then the actual order of the columns within the DBMS.  IDEF standards 
implement the visual paradigm that most of us are used to, that is, the 
primary keys above the line in the entity/table and then the other 
attributes/columns below the line.  In the DBMS the "line" does not 
really exist.  The columns can be in any order.  If you have a three 
part key the first part of the PK can be the second column, the third 
part of the primary key can be in the middle and the second part of the 
primary key can be the next to last column.  Now, for performance 
reasons most people do not implement things that way, but the reality is 
that DBMs do not restrict that from happening.

If you are wanting to have the columns in one order on one DBMS and a 
different order on another DBMS OR you wanted the column order one way 
in the development environment, but a different order in test then 
Mirko's statements are correct.  The level of complexity would be painful.

But if you are meaning that you made a mistake that the DBA catches 
after the implementation then the tool should allow you to change the 
column order as a "correction".  Let me lay out one of my typical scenarios:
I design the logical side, grouping all the attributes together in a way 
that is coherent for discussion.  On the physical side of the model I 
take a best guess on the way the DBA would want the columns sequenced 
for optimal performance.  Sometimes I get this right, sometimes I do 
not.  In those cases where I do not then the physical side needs to be 
updated and re-implemented.  Or as a slight variation things look good, 
but once we are going through testing then the physical columns need to 
be re-sequenced for better performance or because of clustering 
requirements for a particular DBMS.

Does this help?

Thanks,

Craigbert

On 11/23/2010 11:48 AM, Mirko Sertic wrote:
> Hey
>
> Thank you for using ERDesignerNG!
>
> Changing attribute order is not so quite simple, as this is not 
> supported by some database dialects, and would cause complex migration 
> statements if the changed table contains data. What is always possible 
> is to change attribute order in the .mxm file(basically it is XML). 
> Using this patch, attribute ordering can be changed without the UI. If 
> there is still support for changing attribute order, please file a 
> feature request at the SF project tracker. Without the migration 
> limitation, changing attribute order would be very simple:-)
>
> Regards
> Mirko
>
> Am 31.10.2010 05:30, schrieb Phinux Zhang:
>> Hi
>>
>> I like the Mogwai DRDesigner NG, this is the only one I found I can 
>> use on my mac and Win. But why not add a feature so that users can 
>> change the attribute order in a table/view? I can see the application 
>> data is stored as a xml, it should be easy to implement this feature. 
>> If you like, I can do some help.
>>
>> Regards
>>
>> Phinux
>>
>>
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