Entrevista do desenvolvedor Backend Java: perguntas e onde procurar respostas. Parte 2

Um repositório GitHub com uma folha de dicas completa está aqui , e Habr ainda é um bolo.

3 níveis de cache:

• Cache de primeiro nível. Ativado por padrão.
• Cache de segundo nível. Desativado por padrão.
• Cache de consulta. Desativado por padrão.

Mais detalhes:

• Artigo sobre Habré
• Baeldung
• First Level Cache Second Level Cache

Hibernate Vlad Mihalcea:

• High-Performance Java Persistence: 2, 16 — Caching
• How does Hibernate Query Cache work
• How does Hibernate Collection Cache work
• How does Hibernate store second-level cache entries
• How does Hibernate NONSTRICT_READ_WRITE CacheConcurrencyStrategy work
• How does Hibernate TRANSACTIONAL CacheConcurrencyStrategy work
• How does Hibernate READ_ONLY CacheConcurrencyStrategy work
• How does Hibernate READ_WRITE CacheConcurrencyStrategy work

• Eager Loading — , . (@OneToOne, @ManyToOne, @OneToMany, @ManyToMany) fetch = FetchType.EAGER. @OneToOne @ManyToOne.
• Lazy Loading — , . , (@OneToOne, @ManyToOne, @OneToMany, @ManyToMany) fetch = FetchType.LAZY. @OneToMany, @ManyToMany. proxy-, . LAZY- Hibernate, LazyInitializationException.

"N+1" .

Vlad Mihalcea: , LazyInitializationException .

N+1 Hibernate, .

N+1 , N , . N . slow query log, , .

plain sql (jdbc, JOOQ), ( ) . , . " !?". - , - . ? JOIN . .

Hibernate. "N+1", . .

, FetchType.EAGER. N+1. @ManyToOne . JPQL JOIN FETCH . , FetchType.LAZY.

FetchType.LAZY, , N+1. , . — . JOIN FETCH .

JOIN FETCH , bonjour. @OneToMany FetchMode.SUBSELECT — 2 , . .. .

— . @BatchSize .

:

• JPA EntityGraph
• Hibernate FetchProfile

N+1, db-util Vlad Mihalcea. .

JOOQ N+1 , 17- (01:16:36) +. JOOQ.

:

• Vlad Mihalcea:
• Hibernate —
• DOU JPA Hibernate
• JPoint " Hibernate "

: — , . .

Hibernate, @Embeddable. , Serializable equals hashcode.

, , @EmbeddedId.

Vlad Mihalcea Hibernate.

4 JPA (Hibernate):

• MappedSuperclass — . . @MappedSuperClass, @Entity. , , @AttributeOverride . . .
• Single table — . , -. @Entity- @Inheritance(strategy = InheritanceType.SINGLE_TABLE) @DiscriminatorColumn(name = "YOUR_DISCRIMINATOR_COLUMN_NAME") ( DTYPE VARCHAR). @DiscriminatorValue("ThisChildName") , - . , @DiscriminatorFormula, CASE...WHEN — JPA, Hibernate. . . — NULL.
• Joined table — , . , ( ) . @Entity- @Inheritance(strategy = InheritanceType.JOINED). JOIN, CASE...WHEN, _clazz, (0 (), 1, 2 ..) Hibernate .
• Table per class — MappedSuperclass, . . JPA 2.2 ( 2.12) , Hibernate , . @Entity @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS). (@Id) . @AttributeOverride — . UNION . , Hibernate _clazz , (1, 2 ..). NULL AS some_field. .

:

• : ,
• Vlad Mahalcea: MappedSuperclass

, JavaDoc :

• JPA
• Hibernate

JPA 2.2. pdf.

Postgresql. Postgres Pro:

WHERE HAVING , WHERE , ( , ), HAVING . , WHERE ; . HAVING, , . ( , HAVING, , . WHERE.)

:

• How does a relational database work
• How does a relational database execute SQL statements and prepared statements
• How Database Internally Works
• Let's Build a Simple Database
• Database internals

• A — (Atomicity). , .
• C — (Consistency). .
• I — (Isolation). .
• D — (Durability). (, - ).

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• Oracle, MySQL, PostgreSQL, MS SQL
• PostgreSQL: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
• «» MySQL (InnoDB)
• « » Postgres
• , , ?
• :
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• Database Indexes Explained
• Bitmap- B*tree-: ?
• MySQL
• PostgreSQL Java-
• 14 SQL Server,
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• PostgreSQL
• Anatomy of an SQL Index
• SQL Indexing and Tuning e-Book
• Deep dive into Hash indexes for In-Memory OLTP tables
• Indexing based on Hashing
• SQL Server Indexes Interview Questions and Answers
• Top 25 SQL interview questions and answers about indexes
• An in-depth look at Database Indexin

(lock) — .

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:

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• exclusive (write) — , . . , .

— , ( VERSION 0). , , . — (, ) , .

, , . , .

Vlad Mihalcea:

• A beginner’s guide to Java Persistence locking
• A beginner’s guide to database locking and the lost update phenomena
• How do LockModeType.PESSIMISTIC_READ and LockModeType.PESSIMISTIC_WRITE work in JPA and Hibernate
• How does LockModeType.PESSIMISTIC_FORCE_INCREMENT work in JPA and Hibernate
• How does LockModeType.OPTIMISTIC work in JPA and Hibernate
• How does LockModeType.OPTIMISTIC_FORCE_INCREMENT work in JPA and Hibernate
• How to prevent OptimisticLockException with Hibernate versionless optimistic locking
• How does database pessimistic locking interact with INSERT, UPDATE, and DELETE SQL statements
• How does MVCC (Multi-Version Concurrency Control) work
• How does the 2PL (Two-Phase Locking) algorithm work
• How to prevent lost updates in long conversations

:

• .
• Version JPA
• Hibernate – V.
• PostgreSQL: 1.
• PostgreSQL: 2.
• PostgreSQL: 3.
• PostgreSQL: 4.

:

• Pessimistic Locking in JPA
• Optimistic Locking in JPA
• Enabling Transaction Locks in Spring Data JPA
• Deadlock
• Enum LockModeType
• Postgresql
• PostgreSQL Concurrency with MVCC
• Locking Hibernate
• Optimistic locking JOOQ
• Optimistically Locking Your Spring Boot Web Services
• Optimistic and pessimistic locking with SQL

, . . , . , , , .

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:

:

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• microservices.io.
• wiki pros cons.
• SCALING APPLICATIONS: THE SCALE CUBE.
• .
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— Microservice Patterns and Best Practices. Medium .

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:

• : , , , ,
• Visual Guide to NoSQL Systems CAP
• The CAP FAQ
• bigdataschool
• MongoDB stackoverflow
• CAP Theorem IBM
• CAP Theorem and Distributed Database Management Systems
• What is the CAP Theorem? medium

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:

• SOA
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• Wikipedia
• Microservices — Not A Free Lunch!
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• Microservices in a Nutshell. Pros and Cons

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Mock , — .

:

• Mock vs Stub
• Mocks Aren't Stubs
• Test Double
• Test Stub
• Test Spy
• Mock Object
• Fake Object
• Interaction Based Testing Spock Framework
• Mockito
• Mockito Mock vs. Spy in Spring Boot Tests
• Tag: Mockito Bealdung

:

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:

• Java Challengers #3:
• JVM
• Java
• Java Virtual Machine Specification: Invoking Methods, invokevirtual, Linking
• Java Language Specification: Inheritance, Overriding, and Hiding, Conversions and Contexts, Type Inference

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-:

• REST — , REST vs SOAP, Contract First, Code First, HATEOAS, Java Spring
• REST vs SOAP. 1. REST vs SOAP. 2. ?
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• RESTful API
• REST-like API
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• : REST
• 7 REST API
• JAX-WS XSD Restrictions
• REST API Java
• Spring Boot: REST API Java
• RESTful Kotlin Spring boot
• SOAP- Java Apache CXF Spring
• SOAP Web- Spring-WS

-:

• REST — SOAP
• REST 200
• REST API
• RESTful API —
  
  :
• REST GraphQL
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  :
• A Brief Introduction to REST
• REST CookBook
• RESTful Web APIs
• Introduction to Spring Data REST
• What is REST
• Building REST services with Spring
• SOAP Web-
• SOAP

, ! !

Lombok — , , , , . Lombok .

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, , "+" 7-8 — . asm0dey Lombok Lombok . : " , , @SneakyThrows ?" ( ), " @Data. equals ?", " @EqualsAndHashCode StackOverflowException ?".

Lombok — — , . — . Lombok — Lombok, . - , , .

P.S. Lombok onX — (@__ Java 7) . , Spring-.

:

• Project Lombok
• Who Needs Lombok Anyhow
• Be Careful With Lombok
• Don’t use Lombok
• Lombok & Hibernate: How to Avoid Common Pitfalls
• Error handling with @Transactional and @SneakyThrows
• Lombok, sources.jar
• Some Dangers of Using Lombok

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OpenNET — , .

MSDN.

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• Apache JMeter — , opensource, HTTP, HTTPS, FTP, LDAP, SOAP, TCP, shell-. , java-based , JDBC, Message-oriented middleware (MOM) JMS Java Objects.
• LoadRunner — . , Enterprise.
• LoadNinja — , - . , .
• WebLOAD — . , , , CI/CD.
• LoadUI Pro — SOAP UI, . - , API.
• K6 — opensource , . JavaScript. , , , Kafka, Datadog, InfluxDB, JSON StatsD. CI-.
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• Gatling — opensource Scala Netty Akka. Scala, Jenkins.

:

• -
• :
• Gatling
• Top 10
• 9
• 10 Apache JMeter
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• Rest API Load testing with Apache JMeter
• Load Testing with Gatling — The Complete Guide
• -

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• : cgroups
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• Learn Docker & Containers using Interactive Browser-Based Scenarios
• What Is Docker & Docker Container? A Deep Dive Into Docker!
• Docker for beginners

— - Java- — , URL- URL ..

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