---
name: archive228/schema-diff
source: https://app.decimal.ai/s/archive228-schema-diff@1/SKILL.md
source_sha256: a54e2c72ba4e
---

# Schema Diff
Diff old vs new schema. Flag by risk:
- **Destructive** (high): dropped column/table, narrowed type, new NOT NULL on existing rows, dropped index a query relies on.
- **Locking** (high at scale): index without CONCURRENTLY, type change that rewrites the table.
- **Safe**: new nullable column, new table, new index CONCURRENTLY.
For each destructive change: is data lost? is it reversible? is there a backfill? Output a risk-ranked list and a go/no-go with the safe rollout order.