= QueryTrace plugin for Rails

It's nice that ActiveRecord logs the queries that are performed when your actions are executed, 
since it makes it easy to see when you have serious inefficiencies in your application. The next 
question, though, is always, "OK, so where are those being run from?" Before QueryTrace, that 
question could be a real pain to answer, since you'd have to go trawling through your code looking
for the culprit. Once you have QueryTrace installed, though, your logs won't just tell you that you
have a problem, they will pinpoint the location of that problem for you.

== Usage

Either install the QueryTrace as a plugin or as a gem. You can enable QueryTrace by setting the
QUERY_TRACE environment variable like so:

	QUERY_TRACE=true

If you want QueryTrace to always be enabled, create a file in config/initializers, and add the
following line:

	QueryTrace.enable!
	
You can also turn QueryTrace back off at any time:

  QueryTrace.disable!

QueryTrace only outputs traces at the at the DEBUG log level, and honors your log colorization
settings. By default, it outputs up to 20 lines of stack trace. You can adjust this with the depth
accessor:

  QueryTrace.depth = 5

== Runtime Toggling of QueryTrace

Starting with version 0.1.0 of QueryTrace, you can toggle tracing on or off without restarting the
server (thanks to Doug Barth for implementing this). To do so, include QueryTrace in your environment so that
it loads at server startup; you can use an initializer to set its initial state (on or off). Then just
send SIGQUIT (CTRL-\) to your server to switch from enabled to disabled and vice versa.

Important note: initializers load after environment.rb, but before environment-specific configuration
files like development.rb. So make sure you have the QueryTrace gem loaded in environment.rb or 
the runtime toggling will not work. You can use an initializer to selectively turn it on in
development:

QueryTrace.enable! if Rails.env.development?   

== Example

Before:

  Schedule Load (0.023687)   SELECT * FROM schedules WHERE (schedules.id = 3) LIMIT 1
  Resource Load (0.001076)   SELECT * FROM resources WHERE (resources.id = 328) LIMIT 1
  Schedule Load (0.011488)   SELECT * FROM schedules WHERE (schedules.id = 3) LIMIT 1
  Resource Load (0.022471)   SELECT * FROM resources WHERE (resources.id = 328) LIMIT 1


After:

  Schedule Load (0.023687)   SELECT * FROM schedules WHERE (schedules.id = 3) LIMIT 1
    app/models/available_work.rb:50:in `study_method'
    app/helpers/plan_helper.rb:4:in `work_description'
    app/views/plan/_resource_schedule.rhtml:27:in `_run_rhtml_plan__resource_schedule'
    app/views/plan/_resource_schedule.rhtml:24:in `_run_rhtml_plan__resource_schedule'
    app/views/plan/_schedule_listing.rhtml:5:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/_schedule_listing.rhtml:3:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/_schedule_listing.rhtml:1:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/index.rhtml:6:in `_run_rhtml_plan_index'
    vendor/plugins/textmate_footnotes/lib/textmate_footnotes.rb:60:in `render'
  Resource Load (0.001076)   SELECT * FROM resources WHERE (resources.id = 328) LIMIT 1
    app/models/available_work.rb:54:in `div_type'
    app/helpers/plan_helper.rb:6:in `work_description'
    app/views/plan/_resource_schedule.rhtml:27:in `_run_rhtml_plan__resource_schedule'
    app/views/plan/_resource_schedule.rhtml:24:in `_run_rhtml_plan__resource_schedule'
    app/views/plan/_schedule_listing.rhtml:5:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/_schedule_listing.rhtml:3:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/_schedule_listing.rhtml:1:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/index.rhtml:6:in `_run_rhtml_plan_index'
    vendor/plugins/textmate_footnotes/lib/textmate_footnotes.rb:60:in `render'
  Schedule Load (0.011488)   SELECT * FROM schedules WHERE (schedules.id = 3) LIMIT 1
    app/models/available_work.rb:50:in `study_method'
    app/helpers/plan_helper.rb:4:in `work_description'
    app/views/plan/_resource_schedule.rhtml:27:in `_run_rhtml_plan__resource_schedule'
    app/views/plan/_resource_schedule.rhtml:24:in `_run_rhtml_plan__resource_schedule'
    app/views/plan/_schedule_listing.rhtml:5:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/_schedule_listing.rhtml:3:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/_schedule_listing.rhtml:1:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/index.rhtml:6:in `_run_rhtml_plan_index'
    vendor/plugins/textmate_footnotes/lib/textmate_footnotes.rb:60:in `render'
  Resource Load (0.022471)   SELECT * FROM resources WHERE (resources.id = 328) LIMIT 1
    app/models/available_work.rb:54:in `div_type'
    app/helpers/plan_helper.rb:6:in `work_description'
    app/views/plan/_resource_schedule.rhtml:27:in `_run_rhtml_plan__resource_schedule'
    app/views/plan/_resource_schedule.rhtml:24:in `_run_rhtml_plan__resource_schedule'
    app/views/plan/_schedule_listing.rhtml:5:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/_schedule_listing.rhtml:3:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/_schedule_listing.rhtml:1:in `_run_rhtml_plan__schedule_listing'
    app/views/plan/index.rhtml:6:in `_run_rhtml_plan_index'
    vendor/plugins/textmate_footnotes/lib/textmate_footnotes.rb:60:in `render'


== Additional Info

Original Author: Nathaniel Talbott (for Terralien)
Contact: [email protected]
License: MIT
Home: http://github.com/ntalbott/query_trace/
Subversion mirror: https://terralien.devguard.com/svn/projects/plugins/query_trace

Current Author: Mike Gunderloy
Contact: [email protected]
Home: http://github.com/ffmike/query_trace, http://codaset.com/ffmike/query_trace

Copyright (c) 2006 Nathaniel Talbott. All Rights Reserved.