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:
O'Reilly Media - Technology and Business Training
–
Phlip
