Active Record Scanner

A static analysis tool that detects known ORM performance issues with ActiveRecord (e.g. queries inside inner loops).

Installation

$ gem install active_record_scanner

Usage

active_record_scanner "/full/path/to/file/**/*.rb will recursively scan a directory for ActiveRecord queries inside loops. Consider replacing with methods that operate on collections: for instance, replace find_by inside a loop with a where call.

Example:

sgoedecke:parser/ (master*) $ active_record_scanner ./spec/fixtures/test_class.rb 
.
./spec/fixtures/test_class.rb (line 24 column 4) -- called query method '#destroy' in a loop

Development

Run the tests with rake.

References

This tool was inspired by this paper by Junwen Yang: https://newtraell.cs.uchicago.edu/files/ms_paper/junwen.pdf

Unlike the static analysis tools described in the paper, this is (a) written in Ruby and (b) not reliant on a series of regexes.

Todo

• Improve sexp tree traversal (e.g. avoid mutating the tree in normalize!)
• Improve nested array compacting. Remove that awful loop
• Add checks for inefficiences other than queries inside loops
• Add a homebrew formula for easier use

Contributions are welcome.