Railsters:
When you use ActiveRecord, it conglomerates your has_many directives together to produce elaborate queries.
Sometimes these might be a little too elaborate.
I wrote a test helper function that lets you peek under the hood, like this:
sql = inspect_sql do Post.find(:all, :include => { :user => :user_level }, :conditions => { :'user_levels.name' => 'Moderator' }) end
pp sql.statements
The method inspect_sql{} returns an array object full of data about your queries. It comes with accessors (.statements, .keys, .tables, [2], etc.) that let you drill down to specifics. The trace statement 'pp sql.statements' will emit all the SQL SELECT statements that inspect_sql collected.
To optimize those statements, you can use assert_no_match (or assert{ statement !~ /something/ } ) to catch and forbid inefficient or incorrect statements.
This helps you tune your database without writing brute-force tests that simply load thousands of records, query them, and time the results.
Get inspect_sql with the assert_efficient_sql gem, and read more about it here:
-=R