Materialised views and Spring DAO Tests

March 1, 2010

So, you have a materialized view in your DB. That’s great. Give yourself a cookie.

You also have created a set of tests in your DAO layer, using the AbstractTransactionalSpringContextTests. Good for you, again.

But when you try to mix these two together, you may see tests failing and can’t immediately see why. This can happen if you try to get data from the materialized view after attempting to save data to a table that the view accesses.

Well, it’s very simple, and probably pretty obvious. It wasn’t immediately obvious to me why it was failing, and I didn’t really see anything online about it, so hopefully this will stop your search quickly.

First thing to realize is that running your DAO tests through the AbstractTransactionalSpringContextTests is that every test is run in a transaction. That’s great most of the time. Each test will run in a little isolated environment and the changes to the database will be rolled back at the end. You don’t have all kinds of test data strewn about afterwards as if it were the island in Cast Away.

The second thing to realize is that a materialized view will only be updated on commit. There’s a lot more to it than that, but I am not a DBA and that’s all you need to know in general.

So, with those two things in mind, you can see how it might be a problem if you try to write tests against code that uses the materialized view. All is not lost however. If you put an endTransaction() call somewhere in your test, all of the DB calls you’ve made up to that point will be committed. Also, any other calls made after that point will also be committed to the database. Since that happens, you will be on your own to clean up after the test as you see fit. Also, placing an endTransaction will only affect the test you place it in. Any other test will still continue to run and rollback in the normal fashion.

What we ended up doing was making the tests that need to commit to the database small as possible. We then wrapped the endTransaction() function in a function called setTestToCommit() (my co-worker James’ suggestion), so that it makes more sense to read it, and placed it at the beginning of the test.

There’s lots more information about how it works here.