How to show SQL queries run in the Rails console?
When I run queries (e.g. MyModel.where(...)
or record.associated_things
) in the console, how can I see the actual database queries being run so I can gain more understanding of what is happening?
Solution 1:
Rails 3+
Enter this line in the console:
ActiveRecord::Base.logger = Logger.new(STDOUT)
Rails 2
Enter this line in the console:
ActiveRecord::Base.connection.instance_variable_set :@logger, Logger.new(STDOUT)
Solution 2:
In Rails 3+ you can use ActiveRecord::Relation’s to_sql
method:
User.where(:id => 3).to_sql
#=> "SELECT \"users\".* FROM \"users\" WHERE \"users\".\"id\" = 3"
Solution 3:
There is the .explain
method in Rails 4.
(.to_sql
works too, but won't show includes)
Category.includes(:products).explain
=> EXPLAIN for: SELECT "categories".* FROM "categories" 0|0|0|SCAN TABLE categories
EXPLAIN for: SELECT "categories_products".* FROM "categories_products" WHERE "categories_products"."category_id" IN (1, 2) 0|0|0|SCAN TABLE categories_products
EXPLAIN for: SELECT "products".* FROM "products" WHERE "products"."id" IN (1, 2, 3, 4, 5, 6, 7) 0|0|0|SEARCH TABLE products USING INTEGER PRIMARY KEY (rowid=?) 0|0|0|EXECUTE LIST SUBQUERY 1
Solution 4:
Starting from Rails 6 there is more convenient approach: simply add ActiveRecord::Base.verbose_query_logs = true
in console and you will see all SQL calls and places where it was called. More info https://guides.rubyonrails.org/debugging_rails_applications.html#verbose-query-logs
Solution 5:
As from recently, you can use this:
https://github.com/dejan/rails_panel
It consists of developer console panel add-on for chrome, and gem file which needs to be added to your application's Gemfile like this:
group :development do
gem 'meta_request'
end
Then run again:
bundle install
Restart your application, open it, and launch developer console, and you should see it like this: