Tier này dạy gì?
Tier 5 dạy lưu trữ dữ liệu cho backend Go: database/sql,
ORM vs raw SQL, transaction & isolation level, migration zero-downtime, Redis caching,
NoSQL (MongoDB), search (Elasticsearch). Kết thúc với mini-project blog backend dùng
Postgres + Redis + search.
Tiền đề: đã xong Tier 4 (REST API, error handling).
Lesson 54
database/sql, driver, prepared statement, connection pool, NULL handling.
Lesson 55
sqlc / GORM / ent / pgx — trade-off, khi nào dùng cái nào.
Lesson 56
ACID, isolation level, SELECT FOR UPDATE, deadlock, optimistic vs pessimistic lock.
Lesson 57
golang-migrate / atlas, forward/backward, zero-downtime schema change.
Lesson 58
Cache aside, write-through, TTL, cache stampede prevention, Redis data structures.
Lesson 59
Document model, embed vs reference, khi nào NoSQL phù hợp, CAP trade-off.
Lesson 60
Inverted index, query DSL, analyzer, relevance scoring, integrate vào Go service.
Lesson 61
Backend blog: Postgres (CRUD + transaction) + Redis cache + full-text search + migration.