Oracle - Triggers to create a history row on update

Question

First, we currently have the behavior that\'s desired, but it\'s not trivial to maintain when any changes to the database are needed. I\'m looking for anything simpler, more ef

Answer 1

Okay, this is a rewrite. What I missed when I first responded is that the application is storing its History in the main table. Now I understand why @NickCraver is so apologetic about the code.

Well the first thing to do is to hunt down the perpetrators of this design and make sure they never do it again. Storing history like this doesn't scale, makes normal (non-historical) queries more complicated and sabotages relational integrity. Obviously there are scenarios where none of that matters, and perhaps your site is one of them, but in general this is a very bad implementation.

The best way of doing this is Oracle 11g Total Recall. It's an elegant solution, with a completely invisible and effcient implementation, and - by the standards of Oracle's other chargeable extras - quite reasonably priced.

But if Total Recall is out of the question and you really must do it this, don't allow updates. A change to an existing CONTACT record should be an insert. In order to make this work you may need to build a view with an INSTEAD OF trigger. It's still yucky but not quite as yucky as what you have now.

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As of Oracle 11.2.0.4 Total Recall has been rebranded Flashback Archive and is included as part of the Enterprise License (although shorn of the compressed journal tables unless we purchase the Advanced Compress option).

This largesse from Oracle ought to make FDA the normal way of storing history: it's efficient, it's performative, it's an Oracle built-in with standard syntax to support historical queries. Alas I expect to see half-cooked implementations with spatchcocked triggers, broken primary keys and horrible performance for many years yet. Because journalling seems to be one of those distractions which developers delight in, despite the fact that it's low-level plumbing which is largely irrelevant to 99.99% of all business operations.