Stylesheet caching can merge files from different folders and leave relative image paths pointing to the wrong location, so images work locally but fail on the server.

Template-based examples reduce repetition in behavior-driven tests and make repetitive cases easier to maintain.

Whitespace before # in ERB Ruby comments can produce unexpected HTML output; <%# ... %> and newline-indented comments avoid the problem.

Git includes a built-in browser-based repository viewer for local inspection; git instaweb starts a temporary web server, with Apache or lighttpd support.

Spherical distance queries in Graticule can return NULL because MySQL rounding pushes ACOS outside its valid range. Clamping the value to [-1, 1] prevents the zero-distance edge case.

A lightweight database toolkit for Ruby bridges the gap between ActiveRecord and raw SQL when full ORM features are unnecessary.

Two major projects started with DataMapper and later moved to a different ORM, raising questions about the framework’s long-term fit and maintainability.

Multiple column changes in a migration can trigger repeated SQL and slow large tables; change_table can bundle them into one ALTER TABLE statement.

Generate visual database relationship maps from Rails ActiveRecord models for easier schema understanding and documentation.

Front and back audio outputs can stop playing together when jack sensing or auto mute disables one panel. alsamixer can turn off the behavior.

Cached tag lists in ActsAsTaggableOn reduce eager loading and improve performance by storing tag data directly in the model.

Untracked or modified files clutter Git status and can be hidden locally or for everyone with ignore rules and git update-index flags.

Custom right-click menus can be built with HTML in Firefox 8+ instead of relying on browser defaults.

Rails 3 lets applications define custom configuration elements directly, avoiding extra gems or plugins for miscellaneous settings.

Separate gemsets let each Ruby application use its own installed gems. rvm use 1.8.7-p323@makandra_project_xy --create creates and switches to a new gemset.

Bulk test runs can fail with execution expired (Timeout::Error) when Selenium and WebMock interact; upgrading WebMock to 1.7+ resolves the timeout issue.

Classic XLS worksheets stop at 65,535 rows; the Spreadsheet gem writes only XLS, so larger exports need split sheets, extra columns, or XLSX output.

Find records near a latitude/longitude pair by calculating distances in SQL or using acts_as_geocodable for radius-based queries.

Require group in Ubuntu’s default Apache setup fails silently without the group authentication module. Installing libapache2-mod-auth-sys-group enables group-based access control.

Set the Rails environment explicitly when running server-side scripts to avoid using the wrong database or configuration. Rails 2 uses script/runner; Rails 3 uses rails runner.

Language-specific styling can switch background images per locale by using the HTML lang attribute in views and matching selectors in stylesheets.

Thunderbird mailing lists group contacts for easier recipient selection and broadcast email to every member from one address-book entry.

Test database setup can drift from development when schema dumps omit SQL-specific details; choose the right Rake task to keep structure, charset, and collation aligned.

tig can filter commits by path, helping find which changes touched a file, folder, or wildcard pattern without scanning every revision.