Explain all SQL statements in rails
I needed to see all plans for the executed SQL statements in my rails project while in development. so I found this Gem repository and I thought I want to understand how this works, and found that the main piece of code is in this file so I tried to get this code and simplify it and add it to an initializer and the result is the following stripped down version
class Explainer < ActiveSupport::LogSubscriber
def sql(event)
payload = event.payload
return if ignore_payload?(payload)
debug color(ActiveRecord::Base.connection.explain(payload[:sql], payload[:binds]), :yellow)
end
private
IGNORED_PAYLOADS = %w[SCHEMA EXPLAIN].freeze
EXPLAINED_SQLS = /\A\s*(with|select|update|delete|insert)\b/i.freeze
def ignore_payload?(payload)
payload[:cached] ||
IGNORED_PAYLOADS.include?(payload[:name]) ||
payload[:sql] !~ EXPLAINED_SQLS
end
end
Explainer.attach_to :active_record
Just make sure you don’t commit this code or put a condition at the last line to work only in development.
