schema_reaper

https://github.com/aksshatt/schema_reaper

schema_reaper scans a Rails + PostgreSQL app for schema debt that's easy to accumulate and hard to find by hand. It checks your live database against your codebase and flags three kinds of problems: things nothing references anymore (dead columns and dead tables), index trouble (indexes nobody queries, indexes made redundant by a wider index that already covers them, and foreign-key columns with no index at all), and degenerate data (columns that are always NULL, or hold the exact same value in every row). Every finding comes with a confidence score, an estimate of the disk space removing it would reclaim, and a concrete fix. For a column, that's a two-step migration: stop reading it first, then drop it once you've confirmed nothing broke. An optional runtime tracker can sample real production traffic to raise confidence further, for cases a static code scan alone can't settle. Reports come as a colored terminal summary, JSON, Markdown for a PR comment, or SARIF for GitHub code scanning -- plus a CI baseline gate and a trend log to track progress release over release. PostgreSQL only for now. Requires Ruby 2.7 or later. Full usage is in the README.