WARNING: QueryReview is now maintained by a new owner. It is (of course) on github now:

https://github.com/nesquena/query_reviewer

This rails plugin not only runs "EXPLAIN" before each of your select queries in development, but provides a small DIV in the rendered output of each page with the summary of query warnings that it analyzed.

It provides the following features:

• View all EXPLAIN output for all SELECT queries to generate a page (everything that query_analyzer plugin does)
• View SHOW PROFILE ALL output for queries that take significant time
• Rate a page's SQL usage into one of three categories: OK, WARNING, CRITICAL
• Display the number of SELECT, INSERT, UPDATE, and DELETE queries on each page
• Attach meaningful warnings to individual queries
• Provide smart ruby stack traces for each query
• Display interactive summary on page in development modes
• Aggregate near-identical queries and find out their total cost

Developed by Kongregate and David Stevenson, with additional support from Kevin Hall.

To install:

git clone git://github.com/dsboulder/query_reviewer.git vendor/plugins/query_reviewer

OR if necessary (I'm NOT 100% committing to keeping the SVN up to date):

svn export http://query-reviewer.googlecode.com/svn/trunk/ vendor/plugins/query_reviewer

Tested under rails 2.1, 2.0, and 1.2.3

Want to see what it looks like?

http://flouri.sh/2008/4/10/mysql-query-reviewer-now-with-ajax-and-profiling

http://flouri.sh/2008/2/13/mysql-query_reviewer-plugin

http://flouri.sh/2008/9/10/queryreviewer-now-aggregates-identical-queries