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Java & Spring Backend

JPA, Hibernate & Transactions

Persistence context, entity state, fetching, query behavior, transaction boundaries, locking, migrations, and production data access.

24 drillsPractice one at a timeOrdered pathComparison questionConcept questionDebugging scenarioArchitecture scenario

Recommended start

JPA vs Hibernate vs Spring Data

Separates the persistence specification, its ORM implementation, and Spring's repository abstraction while keeping generated SQL visible.

Easy~5 minStep 1 of 24

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1JPA vs Hibernate vs Spring DataRecommended startSeparates the persistence specification, its ORM implementation, and Spring's repository abstraction while keeping generated SQL visible.Comparison questionEasy~5 minJavaSpring BootPractice 2

Practice order

24 drillsOne at a time

1JPA vs Hibernate vs Spring DataUp next / Easy / ~5 min
2Persistence context and EntityManagerMedium / ~7 min
3JPA entity statesMedium / ~7 min

Persistence context and EntityManager

Explains the persistence context as an identity map and unit of work that tracks managed entities through EntityManager.

Concept questionMedium~7 minJavaSpring Boot

Practice

3JPA entity statesConnects transient, managed, detached, and removed states to persist, merge, dirty checking, and safe update workflows.Concept questionMedium~7 minJavaSpring BootPractice

4Dirty checking and flushExplains how managed changes become SQL at flush and why flush is not the same as a durable commit.Concept questionMedium~7 minJavaSpring BootPractice

5First-level vs second-level cacheSeparates mandatory persistence-context identity from optional shared entity caching and its consistency tradeoffs.Comparison questionMedium~7 minJavaSpring BootPractice

6Lazy vs eager fetchingExplains mapping fetch semantics while separating them from the query-specific data shape an endpoint actually needs.Comparison questionMedium~7 minJavaSpring BootPractice

7Diagnose Hibernate N+1Finds repeated association queries with SQL evidence and chooses a bounded fetch or projection without creating a cartesian result.Debugging scenarioHard~10 minJavaSpring BootPractice

8Hibernate fetch strategiesChooses among explicit joins, reusable fetch graphs, and bounded secondary selects based on query shape and cardinality.Comparison questionHard~10 minJavaSpring BootPractice

9JPA relationship ownershipExplains which side writes a foreign key or join table and why both sides of an in-memory bidirectional relationship must remain consistent.Concept questionMedium~7 minJavaSpring BootPractice

10Cascade vs orphanRemovalSeparates propagation of entity operations from deletion of dependent children removed from an owning relationship.Comparison questionMedium~7 minJavaSpring BootPractice

11JPA entity equalityChooses stable entity equality across transient, managed, detached, and proxied instances without breaking hash collections.Architecture scenarioHard~10 minJavaSpring BootPractice

12JPA identifier generationConnects identity, sequence, table, UUID, and assigned identifiers to database support, round trips, ordering, and batch inserts.Comparison questionHard~10 minJavaSpring BootPractice

13Transactional proxy and self-invocationExplains Spring's transactional proxy boundary and why an internal method call does not normally start independent advice.Concept questionHard~10 minJavaSpring BootPractice

14Spring transaction boundariesPlaces a short transaction around one application use case while keeping remote calls, user interaction, and bulk work outside.Architecture scenarioHard~10 minJavaSpring BootPractice

15Spring transaction propagationCompares joining an existing transaction, suspending it for an independent transaction, and using a savepoint-backed nested scope.Comparison questionHard~10 minJavaSpring BootPractice

16Spring rollback rulesExplains default rollback behavior, checked exceptions, rollback rules, swallowed failures, and commit-time exceptions.Concept questionMedium~7 minJavaSpring BootPractice

17Transactional isolation and hintsTreats isolation as concurrency behavior and read-only and timeout as resource hints whose enforcement depends on the transaction stack.Concept questionHard~10 minJavaSpring BootPractice

18Optimistic vs pessimistic lockingChooses version-based conflict detection or database locks from contention, transaction duration, and invariant needs.Comparison questionHard~10 minJavaSpring BootPractice

19Prevent lost updates with @VersionCarries an original version through an API update and turns an optimistic-lock failure into an explicit conflict workflow.Architecture scenarioHard~10 minJavaSpring BootPractice

20JPA query choicesChooses a query representation from static versus dynamic shape, portability, database features, readability, and performance evidence.Comparison questionHard~10 minJavaSpring BootPractice

21Spring Data repository choicesUses generated repository behavior for simple cases and explicit query or implementation boundaries when the use case becomes complex.Architecture scenarioMedium~7 minJavaSpring BootPractice

22Hibernate batch writesCombines JDBC batching, compatible identifiers, periodic flush and clear, bounded transactions, and explicit bulk-operation semantics.Architecture scenarioHard~10 minJavaSpring BootPractice

23LazyInitializationException and OSIVFixes lazy access outside the persistence context with explicit fetch and DTO mapping while explaining the tradeoff of Open Session in View.Debugging scenarioHard~10 minJavaSpring BootPractice

24JPA schema managementUses versioned migrations and staged compatibility instead of letting Hibernate mutate a production schema automatically.Architecture scenarioHard~10 minJavaSpring BootPractice

4

Dirty checking and flush

Medium / ~7 min

5First-level vs second-level cacheMedium / ~7 min

6Lazy vs eager fetchingMedium / ~7 min

7Diagnose Hibernate N+1Hard / ~10 min

8Hibernate fetch strategiesHard / ~10 min

+16 more drills in this section

JPA, Hibernate & Transactions - Java & Spring Backend | Aporeon