Скачать или смотреть How to Maintain Uniqueness in a Multi-Value Field with Elasticsearch's Update By Query

Discover how to avoid adding duplicate values to multi-value fields in Elasticsearch using the update by query feature effectively.
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This video is based on the question https://stackoverflow.com/q/63979449/ asked by the user 'Tom J Muthirenthi' ( https://stackoverflow.com/u/848510/ ) and on the answer https://stackoverflow.com/a/63980595/ provided by the user 'Sahil Gupta' ( https://stackoverflow.com/u/2484748/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Solving Duplicate Values in Multi-Value Fields Using Elasticsearch

Maintaining data integrity is one of the core requirements in database management, especially when handling multi-value fields. If you are using Elasticsearch, you might encounter the challenge of appending new values to an array field while ensuring that duplicates do not creep in. In this guide, we will explore how to achieve this using the update_by_query method in Elasticsearch.

The Problem Statement

Imagine you have an Elasticsearch index with a field that is structured as an array, specifically field_keyword. Whenever you append new values to this field, you want to prevent duplicates from being included. For example, if you execute the same update query that adds the keyword "Invoice # " multiple times, the system should recognize that "Invoice # " is already present and not add it again. How do we implement this?

The Traditional Update Method and Its Shortcoming

Initially, you might be tempted to use a simple script with the following format:

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

Using this method will result in duplicates, as shown below after two executions:

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

The Solution: Conditional Appending

To solve the duplication issue, we need to modify the script to conditionally add a new value only if it does not already exist in the array. Here’s an updated version of the script that does this.

Updated Script

You can alter your original script to include a check for the existence of the value before adding it. The following JSON illustrates this adjustment:

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

Breaking Down the Script

Query Section: The query ensures that we target the correct documents in the index based on specified conditions such as "Invoice Number" and "locale".

Script Section:

The if statement checks whether the field_keyword array already contains the new_field_keyword.

If it doesn't exist, the script adds the keyword to the array, preventing duplication.

Conclusion

Utilizing the update_by_query method in Elasticsearch and modifying the script to check for duplicates is an effective way to maintain the uniqueness of multi-value fields. By following the steps outlined in this guide, you can ensure cleaner, more reliable data in your Elasticsearch setup.

Remember, maintaining data integrity is crucial, and implementing these simple checks can save you from potential future headaches!

If you found this article helpful or have further questions about Elasticsearch, feel free to leave a comment below!