Fix: use external versioning for deletes

[dainiusjocas]

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Problem

If Elasticsearch indexer is highly concurrent, keys are used as ids, and indexer is set to delete records on null values, then not using external versioning for delete requests might corrupt the data: records that should not be deleted end up being deleted.

Solution

Use "version_type" "external" for deletes and as a version number use topic offset.

Does this solution apply anywhere else?

• [ ] yes
• [x] no

Test Strategy

Create an ElasticsearchSinkTask with these properties:

    props.put(ElasticsearchSinkConnectorConfig.KEY_IGNORE_CONFIG, "false");
    props.put(ElasticsearchSinkConnectorConfig.MAX_IN_FLIGHT_REQUESTS_CONFIG, Integer.toString(numOfRecords));
    props.put(ElasticsearchSinkConnectorConfig.BATCH_SIZE_CONFIG, "1");
    props.put(ElasticsearchSinkConnectorConfig.LINGER_MS_CONFIG, "1");
    props.put(ElasticsearchSinkConnectorConfig.BEHAVIOR_ON_NULL_VALUES_CONFIG, "delete");

Then produce a sequence of records with the same key where around half of the records are null, half of them are not null with a version number, and as the last record put a document with the highest version number. Start indexing and expect that in the Elasticsearch index there is exactly one document with the "message" equal to numOfRecords.

Note:

To observe the previous faulty behavior one needs to comment the code which sets the external version for the delete request and run the integration test introduced in this PR several times, the results should be flaky.

Testing done:

• [x] Unit tests
• [ ] Integration tests
• [ ] System tests
• [ ] Manual tests

Release Plan

It is safe to release and backport the code.

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[dainiusjocas]

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[dainiusjocas]

A blog post that explains why this PR is a bug fix: https://www.jocas.lt/blog/post/kc_es_data_consistency/

[dainiusjocas]

test this please

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[yeikel]

What is the status of this change and what prevent it from moving forward? The issue (if still exists) is concerning

[yeikel]

@sp-gupta Would you be able to comment here? Or at least get someone who could?

Thanks!

[dainiusjocas]

@sp-gupta Would you be able to comment here? Or at least get someone who could?

Thanks!

The issue was fixed with other changes a couple of years ago.