我用mongodb有一个基本的独立spring引导应用程序。但是，从数据库检索数据时速度非常慢。例如，从一个产品集合中检索五个文档（all）需要2.5秒，如下所示（实体类），没有getter和setter。

@Document(collection = "products")
public class Product {
    private double itemPrice;
    private int quantity;
    @Indexed(unique = true)
    private String name;
    @Id
    private String productId;
    @DBRef
    private Set<ProductTransaction> productTransactions;
}

存储库类如下所示：

@Repository
public interface ProductRepository extends MongoRepository<Product, String> {

}

服务级别如下所示：

@Service
public class ProductServiceImpl implements ProductService{
   @Autowired
   ProductRepository productRepository;

   public List<Product> getProducts() {
      startTime = System.currentTimeMillis();
      Iterable<Product> products = productRepository.findAll();
      endTime = System.currentTimeMillis();
      System.out.println("Find all products: " + (endTime - startTime));
      return products;
   }
}

application.properties文件：

spring.data.mongodb.host=localhost
spring.data.mongodb.port=27017
spring.data.mongodb.database=productDB

spring.data.mongodb.auto-index-creation=false

pom.xml如下所示：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.3.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.spring.mongodb.ims</groupId>
    <artifactId>ims-desktop-application</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>ims-desktop-application</name>
    <description>This is an app for managing sales and inventories</description>

    <properties>
        <java.version>11</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
        </dependency>
        <dependency>
            <groupId>org.modelmapper</groupId>
            <artifactId>modelmapper</artifactId>
            <version>2.3.0</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

请注意，同样的查询在mongoshell中执行时非常快

db.products.find()

我一定会感谢任何帮助解开为什么从 Spring 启动应用程序的查询非常缓慢。