[exporter/elasticsearch] deprecate/remove dedup config

[axw]

Component(s)

exporter/elasticsearch

Describe the issue you're reporting

The dedup config was introduced in the initial implementation of the Elasticsearch exporter for de-duplicating colliding attributes. This is particularly relevant when using the "Raw" or "ECS encoding modes, where attributes are not nested in unique namespaces. e.g. if one were to add a trace.id attribute to a log record, while also setting the top-level TraceID field, then in ECS mode this would lead to duplicate trace.id attributes being set in the Elasticsearch document; enabling the dedup configuration prevents this.

For better or worse, Elasticsearch rejects documents with objects that have duplicate keys: https://github.com/elastic/elasticsearch/issues/19614. This is not configurable.

The only conceivable reason for making deduplication configurable in the exporter is when you know for absolutely sure that duplicates cannot occur, so you can save a few CPU cycles. This would be the exception rather than the norm, and I think the value does not justify the complexity the configuration introduces.

I propose we:

• deprecate and then remove the dedup config
• always deduplicate object keys

I don't think there's any harm in doing these out of order, essentially making the config a no-op.

[github-actions[bot]]

Pinging code owners:

• exporter/elasticsearch: @JaredTan95 @ycombinator @carsonip

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