api-database-cockroachdb

# CockroachDB Patterns > **Quick Guide:** CockroachDB connects via the standard `pg` driver (PostgreSQL wire protocol). The single most important difference from PostgreSQL: **transaction retries are mandatory**. CockroachDB's serializable isolation means any transaction can fail with SQLSTATE `40001` -- your application MUST catch this and retry the entire transaction. Use `UUID` with `gen_random_uuid()` for primary keys (never `SERIAL` -- sequential IDs cause distributed hotspots). DDL runs as online schema changes in background jobs and **cannot be inside explicit transactions**. Use `AS OF SYSTEM TIME` for follower reads to reduce latency in multi-region deployments. --- <critical_requirements> ## CRITICAL: Before Using This Skill > **All code must follow project conventions in CLAUDE.md** (kebab-case, named exports, import ordering, `import type`, named constants) **(You MUST implement transaction retry logic for SQLSTATE `40001` errors -- CockroachDB WILL return serialization errors under normal operation, unlike PostgreSQL where they are rare)** **(You MUST use `UUID` with `gen_random_uuid()` for primary keys -- NEVER use `SERIAL` or sequential IDs, which cause distributed write hotspots)** **(You MUST NOT put DDL statements inside explicit transactions -- most DDL runs as background jobs and can fail at COMMIT time with a partially applied state. `CREATE TABLE`/`CREATE INDEX` are exceptions but the safest practice is always: one DDL statement per implicit tran...