Run performance tests without dumping database

The test environment is designed for testing that stuff works, not for
performance testing. In order for tests to be repeatable they have to
always work on the same data, which is why the test database is
reloaded for each test, either from fixtures or, more often nowadays,
using Factories.

The test environment is not appropriate for performance testing
anyway, to do this you would have to set up a parallel production
environment in order that it correctly mimics your real environment.

Colin

Hi,

I’m trying to build a simple performance test on a rails 3 app that operates

on a large database (~150GB). We copy production data to our dev/test setup

every night so that we have a realistic environment for development.

I followed the guide on creating a test and tried to run it using

$ rake test:benchmark

Unbelievably, this tried to drop my test database!!! Fortunately it didn’t

have permission to do this and failed.

Is there a way to skip this step and

just run the test against the DB as it exists already. From the guide, it

seems like most rails apps have their test data in yaml files or something

but I don’t understand how this would scale to a production environment.

Code that works well on 100 or so database rows is not necessarily going to

work well on millions of rows.

The test environment is designed for testing that stuff works, not for

performance testing.

If this is true, someone should tell that to the official guide maintainers

http://guides.rubyonrails.org/performance_testing.html

The test environment is not appropriate for performance testing

anyway, to do this you would have to set up a parallel production

environment in order that it correctly mimics your real environment.

Exactly! We have this. I just wondered if there was a “rails/ruby way” of writing and running performance tests against this environment. The scaffolding builds a tests/performance directory so I assumed there was.

> Hi,
>
> I'm trying to build a simple performance test on a rails 3 app that
> operates
> on a large database (~150GB). We copy production data to our dev/test
> setup
> every night so that we have a realistic environment for development.
>
> I followed the guide on creating a test and tried to run it using
>
> $ rake test:benchmark
>
> Unbelievably, this tried to drop my test database!!! Fortunately it
> didn't
> have permission to do this and failed.
> Is there a way to skip this step and
> just run the test against the DB as it exists already. From the guide,
> it
> seems like most rails apps have their test data in yaml files or
> something
> but I don't understand how this would scale to a production environment.
> Code that works well on 100 or so database rows is not necessarily going
> to
> work well on millions of rows.

The test environment is designed for testing that stuff works, not for
performance testing.

If this is true, someone should tell that to the official guide maintainers

http://guides.rubyonrails.org/performance_testing.html

That munching sound you can hear is me eating my words.

The test environment is not appropriate for performance testing
anyway, to do this you would have to set up a parallel production
environment in order that it correctly mimics your real environment.

Exactly! We have this. I just wondered if there was a "rails/ruby way" of
writing and running performance tests against this environment. The
scaffolding builds a tests/performance directory so I assumed there was.

I see from the guide section 1.7 that for performance test environment
is close to the production environment. Munch munch.

So to get back to your original question this might be helpful, though
I have not tried it myself. It is a bit old so may need tweaking for
Rails 3. Does anyone else have suggestions?
http://m.onkey.org/running-rails-performance-tests-on-real-data

Colin

Aha, thanks for this link. That helps a lot.