Resolving Document ID Evaluation Issues in Elasticsearch with Logstash

Описание: Learn how to prevent data duplication in Elasticsearch by correctly evaluating document IDs in Logstash with a straightforward solution.
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Resolving Document ID Evaluation Issues in Elasticsearch with Logstash

When using Logstash to ingest data into Elasticsearch, one common challenge is ensuring that document IDs are correctly evaluated to avoid data duplication. If you're struggling with setting a string for the document_id based on a column in your database, you're not alone. Many users encounter issues where the specified document_id string does not evaluate as expected, leading to complications in managing unique documents in Elasticsearch.

In this post, we’ll explore the problem of non-evaluating document IDs and walk through a solution that can help you effectively configure your Logstash setup for proper data ingestion.

The Problem

During the data ingestion process, you want to set the document_id to a unique identifier to avoid inserting duplicate records. In your case, you were trying to evaluate the document ID using the configuration:

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

However, this did not yield the expected outcome, leading to confusion about why the ID is not being evaluated. As a result, you found that the record ends up with an unexpected row ID that doesn’t correspond to your intended unique identifier.

Key Issues

Document IDs were not evaluated as expected.

The field name transformation potentially caused mismatches when querying for column values.

The use of ECS (Elastic Common Schema) being disabled may add to complexity, though it is less relevant in this specific case.

The Solution

The primary reason your document_id did not get evaluated correctly stems from Logstash's default behavior of folding field names to lowercase. This means that instead of having a field called projectsRowId, Logstash generates a field named projectsrowid. Consequently, the document_id string refers to a non-existent field.

To resolve this issue, follow these steps:

Step 1: Modify Your JDBC Input Configuration

Add the lowercase_column_names parameter to your JDBC input configuration and set it to false. This change will retain the original casing of your column names, including projectsRowId. Here’s how your configuration should look:

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

Step 2: Update the Document ID Reference

After ensuring that the field name projectsRowId retains its original case, update the document_id reference in your output configuration:

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

Conclusion

By modifying the Logstash configuration to prevent the alteration of field name casing, we can ensure that the document_id evaluates correctly. This adjustment allows for unique identification of documents within Elasticsearch, preventing data duplication and ensuring a smooth ingestion process.

If you continue to face challenges, consider checking for any ongoing discussions in the community about Logstash configurations or potential bugs in particular versions of the software.

By following the steps outlined above, you will enhance your Logstash setup and streamline your data ingestion process with Elasticsearch.