phase-4-databases-persistence.md

title	Phase 4 - Databases & Persistence
nav_order	4
has_children	true
permalink	/phase-4-databases-persistence

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Phase 4 - Databases & Persistence

Goal: Interact with relational databases correctly - raw JDBC, JPA/Hibernate ORM, Spring Data repositories, schema migrations, and connection-pool management. By the end of this phase you can design a persistence layer from scratch and explain exactly what SQL every layer generates.

Module	Topic	Status
31	JDBC - DriverManager, PreparedStatement, ResultSet, transactions, HikariCP, batch	✅
32	JPA & Hibernate - entities, relationships, fetch types, N+1, cache, JPQL, Criteria API	✅
33	Spring Data JPA - repositories, derived queries, @Query, projections, pagination	✅
34	NoSQL - MongoDB documents & aggregations, Redis hash/list/pub-sub	✅
35	Database Migration - Flyway versioned migrations, Liquibase changeSets, zero-downtime	✅

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