[BAEL-4637] Performance difference between save() and saveAll() in Spring Data (#10177)

* [BAEL-4637] Performance difference between save() and saveAll() in Spring Data

* Apply suggestions from code review

* Rename IBookRepository.java to BookRepository.java

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/saveperformance/Book.java

@@ -0,0 +1,25 @@
+package com.baeldung.spring.data.persistence.saveperformance;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+
+@Entity
+public class Book {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private long id;
+
+    private String title;
+    private String author;
+
+    public Book(final String title, final String author) {
+        this.title = title;
+        this.author = author;
+    }
+
+    public Book() {
+    }
+}

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/saveperformance/BookApplication.java

@@ -0,0 +1,48 @@
+package com.baeldung.spring.data.persistence.saveperformance;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.context.event.ApplicationReadyEvent;
+import org.springframework.context.event.EventListener;
+
+import java.util.ArrayList;
+import java.util.List;
+
+@SpringBootApplication
+public class BookApplication {
+
+    @Autowired
+    private BookRepository bookRepository;
+
+    public static void main(String[] args) {
+        SpringApplication.run(BookApplication.class, args);
+    }
+
+    @EventListener(ApplicationReadyEvent.class)
+    public void executePerformanceBenchmark() {
+
+        int bookCount = 10000;
+
+        long start = System.currentTimeMillis();
+        for(int i = 0; i < bookCount; i++) {
+            bookRepository.save(new Book("Book " + i, "Author " + i));
+        }
+        long end = System.currentTimeMillis();
+        bookRepository.deleteAll();
+
+        System.out.println("It took " + (end - start) + "ms to execute save() for " + bookCount + " books");
+
+        List<Book> bookList = new ArrayList<>();
+        for (int i = 0; i < bookCount; i++) {
+            bookList.add(new Book("Book " + i, "Author " + i));
+        }
+
+        start = System.currentTimeMillis();
+        bookRepository.saveAll(bookList);
+        end = System.currentTimeMillis();
+
+        System.out.println("It took " + (end - start) + "ms to execute saveAll() with " + bookCount + " books\n");
+
+    }
+}

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/saveperformance/BookRepository.java

@@ -0,0 +1,7 @@
+package com.baeldung.spring.data.persistence.saveperformance;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface BookRepository extends JpaRepository<Book, Long> {
+
+}