Re: Changing from horizontal to single table inheritance
Re: Changing from horizontal to single table inheritance
- Subject: Re: Changing from horizontal to single table inheritance
- From: Chuck Hill <email@hidden>
- Date: Fri, 04 Oct 2013 17:01:57 +0000
- Thread-topic: Changing from horizontal to single table inheritance
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On 2013-10-04 9:09 AM, "Mark Wardle" wrote:
Hi all,
When I originally planned the schema used for our clinical application, I used horizontal inheritance. As use has increased, I perceive that horizontal inheritance will not scale for more and more entities. Perhaps I should spend time measuring the performance
impact, but I am planning on ever increasing the number of child entities (they act as data collection forms) and so I think single-table inheritance is a better fit.
Yes, it is.
I have two questions.
1. Is there an easy way of migrating? I can see that I could set-up a wholly new type of entity / sub entities and then manually migrate old entity data into the new ones. This sounds like a considerable piece of work.
You should be able to migrate the model fairly painlessly. For the data, I think you will end up with a script of INSERT INTO … VALUE SELECT FROM statements.
2. What happens in single-table inheritance if you have a clash of property names but the column name is different (or for that matter the same).
I think that should be OK. EOs can't change entity type so EOF should do the right thing for each sub-entity in terms of moving data to and from the columns.
Chuck
--
Chuck Hill
Executive Managing Partner, VP Development and Technical Services
Practical WebObjects - for developers who want to increase their overall knowledge of WebObjects or who are trying to solve specific problems.
http://www.global-village.net/gvc/practical_webobjects
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