How to Use Composite Primary Key Mapping in Spring Data Elasticsearch

Learn how to implement a `Composite Primary Key` in Spring Data Elasticsearch for your entity model. Optimize your Elasticsearch data management with this guide.
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Understanding Composite Primary Keys in Spring Data Elasticsearch

When working with databases, one of the fundamental concepts is the primary key. However, in certain scenarios, a single attribute may not suffice to uniquely identify a record. This is where the idea of a composite primary key comes into play. In this guide, we will explore how to implement composite primary key mapping in Spring Data Elasticsearch, specifically focusing on an example with a Product entity.

The Scenario

Let's consider you have an entity named Product. You want to use a composite key that combines the attributes id and name. The goal is to create a model where Elasticsearch recognizes this combination as the unique identifier for our Product instances.

Here’s the initial structure of the Product entity:

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However, Elasticsearch has some limitations concerning composite keys, meaning we need to adjust our approach.

The Solution to Composite Key Mapping

Step 1: Rename the Id Property

The first thing we need to do is rename the id property. By changing its name (for example, to documentId), we avoid the limitation in Spring Data Elasticsearch where only one field can be annotated with @ Id. Here’s how the updated field looks:

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Step 2: Create a Method for Elasticsearch ID

Next, we need to add a method that returns the composite key. This method will be marked with @ Id and @ AccessType(AccessType.Type.PROPERTY). This approach allows us to dynamically generate a unique identifier based on both documentId and name.

Here’s what the method looks like:

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Step 3: Implement a No-op Setter

Due to a known issue in Spring Data Elasticsearch, you'll also have to provide a no-op setter for the method. This prevents unwanted behavior when the entity is updated after saving or when reading from the Elasticsearch index:

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The Complete Entity

Combining everything, your final CompositeEntity class should look like this:

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Step 4: Define the Repository

Finally, you'll create a repository interface that manages your CompositeEntity objects:

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This straightforward setup enables you to handle composite keys efficiently.

Conclusion

Implementing composite primary keys in Spring Data Elasticsearch involves a few careful adjustments to your entity definitions. By following the steps outlined above, you can effectively use a combination of attributes as a unique identifier for your data in Elasticsearch. With this knowledge, you can enhance your data management strategies, ensuring your application maintains integrity even with complex data structures.

Now that you’ve understood the process, feel free to implement it in your project and enjoy the seamless data handling in Elasticsearch!

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