Alex Chaffee's blog
Hoping to improve performance, we changed a query to use the :include condition like this:
Project.find(id, :include => :stories)
and we noticed two things:
- ActiveRecord decided to turn that into a LEFT OUTER JOIN. Egads! This drastically slowed things down (although we didn't notice until several days later, when we ran a real load test with production data).
- acts_as_paranoid did not manage to stick it's little "and deleted_at = nil" phrase into the query. This meant that "deleted" stories showed up when they weren't supposed to.
So that's two gotchas for the price of one.
In email, Nick pointed out that the joining behavior is documented and appropriate ("otherwise if there is a nil association (eg a project without any stories) you wouldn't get a project back even though it exists!") and Miho rejoined that AR can be dangerous because it changes what looks like beautiful, elegant Ruby into nasty, ugly, hard-to-understand SQL under the hood.
Ever do "less log/development.log" and see the following?
ESC[4;35;1mSQL (0.001084)ESC[0m ESC[0mSET character_set_results = utf8;ESC[0m
ESC[4;36;1mSQL (0.001792)ESC[0m ESC[0;1mSHOW TABLESESC[0m
Wouldn't it be nicer to see the colorization like when you're tailing the log with tail -f? Try using -R:
less -R log/development.log
Then you'll see
SQL (0.001084) SET character_set_results = utf8;
SQL (0.001792) SHOW TABLES
A bit more legible, eh wot old chaps?
Works on Mac and Cygwin too.
And -X makes it not clear the screen when you stop less, so you get to keep seeing what you were just seeing.
So that means you may want to put
alias less="less -RX"
or
export LESS="-RX"
in your .bash_profile.
Also, if you don't want the fancy colors at all, specify
ActiveRecord::Base.colorize_logging = false
in your environment file (e.g. test.rb.) We're doing that in our test.rb so we can more clearly read the output from our CruiseControl build.