Where to put your code - Database vs. Application?

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I have been developing web/desktop applications for about 6 years now. During the course of my career, I have come across application that were heavily written in the database using stored procedures whereas a lot of application just had only a few basic stored procedures (to read, insert, edit and delete entity records) for each entity.

I have seen people argue saying that if you have paid for an enterprise database use its features extensively. Whereas a lot of "object oriented architects" told me its absolute crime to put anything more than necessary in the database and you should be able to drive the application using the methods on those classes?

Where do you think is the balance?

Thanks, Krunal

Answer 1

Reading these answers, I'm quite confused by the lack of understanding of database programming. I am an Oracle Pl/sql developer, we source control for every bit of code that goes into the database. Many of the IDEs provide addins for most of the major source control products. From ClearCase to SourceSafe. The Oracle tools we use allow us to debug the code, so debugging isn't an issue. The issue is more of logic and accessibility.

As a manager of support for about 5000 users, the less places i have to look for the logic, the better. If I want to make sure the logic is applied for ALL applications that use the data , even business logic, i put it in the DB. If the logic is different depending on the application, they can be responsible for it.

Answer 2

I'm in the object oriented architects camp. It's not necessarily a crime to put code in the database, as long as you understand the caveats that go along with that. Here are some:

1. It's not debuggable
2. It's not subject to source control
3. Permissions on your two sets of code will be different
4. It will make it more difficult to track where an error in the data came from if you're accessing info in the database from both places

Answer 3

@Thomas Owens: (re source control) Yes, but that's not source control in the same sense that I can check in a .cs file (or .cpp file or whatever) and go and pick out any revision I want. To do that with database code requires a potentially-significant amount of effort to either retrieve the procedure from the database and transfer it to somewhere in the source tree, or to do a database backup every time a minor change is made. In either case (and regardless of the amount of effort), it's not intuitive; and for many shops, it's not a good enough solution either. There is also the potential here for developers who may not be as studious at that as others to forget to retrieve and check in a revision. It's technically possible to put ANYTHING in source control; the disconnect here is what I would take issue with.

(re debuggable) Fair enough, though that doesn't provide much integration with the rest of the application (where the majority of the code could live). That may or may not be important.

Answer 4

Well, if you care about the consistency of your data, there are reasons to implement code within the database. As others have said, placing code (and/or RI/constraints) inside the database acts to enforce business logic, close to the data itself. And, it provides a common, encapsulated interface, so that your new developer doesn't accidentally create orphan records or inconsistent data.

Answer 5

I'm coming from almost the same background and have heard the same arguments. I do understand that there are very valid reasons to put logic into the database. However, it depends on the type of application and the way it handles data which approach you should choose.

In my experience, a typical data entry app like some customer (or xyz) management will massively benefit from using an ORM layer as there are not so many different views at the data and you can reduce the boilerplate CRUD code to a minimum.

On the other hand, assume you have an application with a lot of concurrency and calculations that span a lot of tables and that has a fine-grained column-level security concept with locking and so on, you're probably better off doing stuff like that directly in the database.

As mentioned before, it also depends on the variety of views you anticipate for your data. If there are many different combinations of columns and tables that need to be presented to the user, you may also be better off just handing back different result sets rather than map your objects one-by-one to another representation.

After all, the database is good at dealing with sets, whereas OO code is good at dealing with single entities.

Answer 6

My personal preference is to try and keep as much logic and configuration out of the database as possible. I am heavily dependent on Spring and Hibernate these days so that makes it a lot easier. I tend to use Hibernate named queries instead of stored procedures and the static configuration information in Spring application context XML files. Anything that needs to go into the database has to be loaded using a script and I keep those scripts in version control.