Deriving join SQL incredibly slow on Rails 3

rubyonrails-talk
1

I was trying to work out why a page on my site was so slow. The queries themselves seemed to be executing pretty quickly so I tried playing around to see if Rails was causing the overhead.

I changed the line:       records = Record.order(:col).joins(:table1) to:       records = Record.order(:col).joins('INNER JOIN "table1" ON "table1"."table2_id" = "table2"."id"')

...and this shaved 100s of ms off the page render time.

Can anyone else try this and confirm it?

Shim

2

There are some performance issues with arel (Active Relations) 1.0.x (which is used by Rails 3.0.1). The 2.0.1 version is supposed to fix these issues.

I believe that the next version of Rails 3 will use arel 2.0.x.