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database-migrations

How to write safe, reversible, zero-downtime database schema migrations — additive-first changes, the expand/migrate/contract pattern, batched backfills, concurrent index builds, safe NOT NULL, rollbacks, and the locking pitfalls that cause outages. A deep reference with runnable checks.

$npx vanara install database-migrations

Free & open source (Apache-2.0) — view the source on GitHub.

Overview

A migration runs against live data while old code may still be serving traffic. The dangerous moment is never the steady state before or after — it's the in-between, when the schema has changed but not every app instance has. Design every change to be correct *during* that window. Heavy detail lives in references/; copy-paste material in examples/; a runnable safety check in scripts/.

What it covers

Details

Tier
Free
Version
2.0.0
Depth
3 references · 2 examples · 1 runnable scripts
Verification
1/1 runnable checks passing ✓
Runs on
Your own Claude Code — no API keys
api-paginationImplement correct, fast API pagination — cursor vs offset trade-offs, opaque cursor encoding, stable sort keys, page-size limits, total-count costs, and consumer-side iteration that survives inserts, deletes, and retries. With runnable cursor checks.app-store-optimizationHow to optimize an app-store listing (ASO) for discovery and conversion — title, subtitle, keywords, screenshots, icon, ratings, and the metadata that drives installs. A deep reference with worked Apple and Google listings and a runnable listing linter.audit-loggingDesign tamper-evident audit logs that satisfy security and compliance — what to record (who/what/when/where/outcome), what to never log (secrets/PII), structured immutable events, hash-chaining for tamper-evidence, retention, and access control. A deep reference with runnable validation.background-jobsDesign background job systems that don't lose or double work — enqueue-after-commit, retry policies with jitter, idempotent handlers, visibility timeouts, priority lanes, scheduled and recurring jobs, worker scaling, and observability for async work. With a runnable retry-policy check.backup-and-recoveryDesign and operate a tested backup and disaster-recovery strategy — the 3-2-1 rule, RPO/RTO targets, full vs incremental vs differential, point-in-time recovery, encryption, offsite/immutable copies, retention, and the restore drills that prove a backup actually works.c4-diagrammingDocument software architecture with the C4 model (Context, Container, Component, Code) as text-based diagrams in version control. Covers the four abstraction levels, notation discipline, when to draw each level (and when to stop), supplementary diagrams, and Mermaid/Structurizr tooling.
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