Скачать или смотреть How to Use In-Memory Map-Based Job Repository with Spring Batch and JPA

A guide to resolving issues when configuring Spring Batch with in-memory Map-based job repositories without creating PostgreSQL metadata tables in your Spring Boot application.
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Solving the Spring Data JPA Issue When Using Spring Batch

When working with Spring Batch in a Spring Boot application, you might encounter issues where your data is not saved to the database as expected. This challenge can arise particularly when configuring the in-memory job repository and trying to avoid the creation of unnecessary metadata tables in your PostgreSQL database. In this guide, we will delve into this problem and explore how to implement a solution effectively.

The Problem

Imagine you have a Spring Boot application seamlessly interacting with a PostgreSQL database using JPA. You are using Spring Batch for managing batch processing, including reading from files and writing to the database. The issue arises when you want to utilize an in-memory Map-based job repository, instead of relying on metadata tables automatically created in your database by Spring Batch.

The core of the issue primarily revolves around dual data source configurations and ensuring that your writing operations, involving JPA, still function as intended. In addition, it is essential that while your program leverages an in-memory repository, your data persists correctly in your main database.

Example Scenario

Consider the following simple configuration for your batch job:

BatchConfiguration.java: Handles your batch steps and jobs.

UserRepository.java: Your JPA repository that communicates with the PostgreSQL database.

UserItemWriter.java: The implementation that writes processed data back into your PostgreSQL database.

However, when trying various approaches, you notice that the data is not committed to PostgreSQL at all, suggesting some fundamental configuration problems need to be addressed.

The Solution: Defining Multiple Data Sources

To resolve this issue, you need to configure multiple data sources within your Spring Boot application. Here are the steps to implement this:

Step 1: Configuration of the Data Sources

You will need to configure one data source for the Spring Batch metadata and another for the PostgreSQL database for your job processing. In your application.properties, you can specify the configurations as follows:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Create the In-Memory Data Source

You create a manually defined data source for the Spring Batch metadata. Here's how you can define it using Spring configuration:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Configure PostgreSQL Data Source

Next, you need to set up your PostgreSQL data source for the job processing as shown below:

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Verify Repository Functionality

At this stage, ensure that your custom repositories correctly point to the specified data sources. This separation allows Spring Batch to handle the in-memory storage without interfering with your PostgreSQL data persistence layer, allowing for a smooth flowing processing environment.

Conclusion

By implementing these configurations, you effectively utilize the in-memory Map-based job repository in Spring Batch while maintaining data storage and integrity in your PostgreSQL database. This approach prevents unnecessary metadata table creation while ensuring that job repositories work as expected.

If you have found this guide helpful, or if you need further assistance with Spring Batch or Spring Data JPA, feel free to leave your feedback or questions in the comments below!