opensearch-project / opensearch-project/data-prepper

Reduce duplicates from the opensearch source for Scroll searches

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bug
Dominant language
Java
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374
Forks
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Avg merge
3d 18h
Merged PRs (30d)
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Description

Is your feature request related to a problem? Please describe.
I'm seeing duplicate documents being ingested into my sink when using an opensearch source that's pointing to an Amazon OpenSearch domain running Elasticsearch 7.10. After looking into the Elastic documentation and the code I believe that this is the root cause of the duplicates

We recommend you include a tiebreaker field in your sort. This tiebreaker field should contain a unique value for each document. If you don’t include a tiebreaker field, your paged results could miss or duplicate hits.

https://www.elastic.co/guide/en/elasticsearch/reference/7.10/paginate-search-results.html

The scroll request that's being created in the ElasticsearchAccessor only sorts based on a single field: https://github.com/opensearch-project/data-prepper/blob/2919e9942e51dcb02547b209d6ee3a3fe420944f/data-prepper-plugins/opensearch/src/main/java/org/opensearch/dataprepper/plugins/source/opensearch/worker/client/ElasticsearchAccessor.java#L159-L164

Describe the solution you'd like
Add a secondary sort field to the Elasticsearch Scroll request.

Something similar is already done for OpenSearch PointInTime requests: https://github.com/opensearch-project/data-prepper/blob/87c560a3964175231b35f87fa6ab0cbc626271bb/data-prepper-plugins/opensearch/src/main/java/org/opensearch/dataprepper/plugins/source/opensearch/worker/client/OpenSearchAccessor.java#L114-L131

Describe alternatives you've considered (Optional)
N/A

Additional context
Add any other context or screenshots about the feature request here.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start in data-prepper-plugins/opensearch/src/main/java/org/opensearch/dataprepper/plugins/source/opensearch/worker/client/ElasticsearchAccessor.java at the scroll request around lines 159-164. Compare the secondary sort handling in OpenSearchAccessor.java around lines 114-131, then verify that the scroll request includes a tiebreaker and no longer produces duplicate documents.

Written by the indexing model from the issue text.

Assessment

Tech stack
java
Domain
data-engineering
Issue type
Feature
Difficulty
2/5
Estimated time
1-3 hours
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
58/100

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