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?
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Andrew, if you need also to run commands in broweser you can use github.com/igorkasyanchuk/rails_dbIgor Kasyanchuk– Igor Kasyanchuk2015-10-16 16:40:06 +00:00Commented Oct 16, 2015 at 16:40
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See also this answer: stackoverflow.com/a/1576221/446106mwfearnley– mwfearnley2016-10-05 15:29:57 +00:00Commented Oct 5, 2016 at 15:29
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9 Answers
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)
5 Comments
randombits
Perfect, just what I needed. Have any recommendation where to go find small tricks such as these are documented?
John Topley
Sure. slash7.com/2006/12/21/secrets-of-the-rails-console-ninjas and stackoverflow.com/questions/123494/… Plus railscasts.com is always good.
rogerdpack
This works for rails 3+ but not 2, see stackoverflow.com/a/1576221 if you're there still :)
Hula_Zell
And to disable it again:
ActiveRecord::Base.logger = nil
23tux
I've been here so many times, when I type "rails" in chrome, it displays this page as the top result
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"
Comments
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
1 Comment
abhishek77in
It took me so much time to find the
.explain will do the job and not .to_sql. And .explain still does not provide sql query in raw format which I can run in pg console. But I needed the raw query to explain and analyze. I guess will have to do with explain for now.I just wanted to give our production console the same behavior I’m used to on dev, where all SQL queries are reported to the console.
Rails.logger.level = 0
3.0.3 :001 > Rails.logger.level = 0
=> 0
3.0.3 :002 > User.last
User Load (0.7ms) SELECT `users`.* FROM `users` ORDER BY `users`.`id` DESC LIMIT 1
=> #<User:…>
1 Comment
Rorrim
Equivalent to
Rails.logger.level = :debugStarting 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
3 Comments
Jarno Lamberg
There should be no need to turn it on, anymore, as it should be nowadays on by default: "Verbose query logs are enabled by default in the development environment logs after Rails 5.2."
Sarah Vessels
This seems to be deprecated: "ActiveSupport::DeprecationException: DEPRECATION WARNING: ActiveRecord::Base.verbose_query_logs= is deprecated and will be removed in Rails 7.1."
Dave Powers
This method has indeed been deprecated, but it was moved out of
AR::Base and is now available as ActiveRecord.verbose_query_logs as of Rails 7.0.For Rails v"6.1.7.3" the following combination worked for me:
ActiveRecord::Base.logger = Logger.new(STDOUT)
ActiveRecord::LogSubscriber.attach_to :active_record
Comments
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:
Comments
There are a few configuration parameters that control whether SQL queries are printed to the log.
(This answer is based on Rails 6.0.)
First, confirm that the logger is configured and its @logdev has a @dev or @filename that matches your expectations.
pry(main)> ActiveRecord::Base.logger
=> #<ActiveSupport::Logger:0x00007fd47b400900
...,
@logdev=
#<Logger::LogDevice:0x00007fd47b400a90
@binmode=false,
@dev=#<File:log/development.log>,
@filename="log/development.log",
...>,
...>
Next, ensure that the logger level is set to DEBUG:
ActiveRecord::Base.logger.debug!
Try running a query to see whether the issue has been fixed:
> ActiveRecord::Base.connection.exec_query 'SELECT 1'
SQL (0.1ms) SELECT 1
If queries are being printed to the log file (e.g. log/development.log) but not to the console, then you may need to do this:
ActiveRecord::Base.logger.extend(
ActiveSupport::Logger.broadcast(ActiveSupport::Logger.new(STDOUT))
)
If you're still not getting SQL queries, then the ActiveRecord::LogSubscriber may not be listening to events (e.g. because some libraries deactivate it). Activate it:
ActiveRecord::LogSubscriber.attach_to :active_record
Comments
I prefer to set up logger level in config/application.rb:
config.after_initialize do
Rails.logger.level = (ENV['LOG_LEVEL'] || Logger::INFO).to_i
end
On production my ENV['LOG_LEVEL'] will be set to the value of Logger::INFO and on my local machine it'll be Logger::DEBUG.
