# Golang Database

> Implement Go database access with context, pool tuning, transaction boundaries, and repository seams. Use when building repositories, tuning `sql.DB` or `pgx`, or reviewing DB transaction flow in Go.

- Skill: `hoangnguyen0403/golang-database` (Agent Skill, multi-file: 4 files)
- Install (CLI): `npx skillmds add hoangnguyen0403/golang-database`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hoangnguyen0403/golang-database/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Data & Analytics
- Author: HoangNguyen0403 (https://skillmd.com/u/hoangnguyen0403)
- Updated: 2026-08-19
- Page: https://skillmd.com/skills/hoangnguyen0403/golang-database

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# Golang Database

## **Priority: P0 (CRITICAL)**

## Rules

- Prefer explicit SQL or generated query layers when performance and shape matter.
- Configure the pool; defaults are rarely enough for real traffic.
- Pass `context.Context` to every query path.
- Keep transaction ownership at the service/use-case boundary, not split across handlers.

## Recipe

1. **Choose the access layer**: `database/sql`, `pgx`, `sqlc`, or ORM only if the team already standardizes on it.
2. **Tune the pool**: max open, max idle, connection lifetime, and idle lifetime.
3. **Hide storage details behind repository methods** or query services.
4. **Close rows and inspect `rows.Err()`**.
5. **Wrap multi-step writes in one transaction** and propagate context/deadlines.

## Verify

- [ ] Query methods accept `context.Context`.
- [ ] Pool settings are explicit.
- [ ] Rows are closed and iteration errors checked.
- [ ] Transaction scope matches one business action.
- [ ] Retry/idempotency policy is clear for contested writes.

## Anti-Patterns

- **No global db var**: inject DB connection via constructor.
- **No context-less queries**: use `QueryContext`/`ExecContext`; bare queries ignore timeouts.
- **No leaked rows**: always `defer rows.Close()` and check `rows.Err()`.
- **No transaction split-brain**: handler, repo, and service cannot each open their own transaction for one unit of work.

## References

- [Framework Map](../references/framework-map.md)
- [Repository Pattern Implementation](references/repository-pattern.md)
- [Connection Tuning](references/connection-tuning.md)