Add _metric_names_hash field to OTel metric mappings #120952
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If metrics that have the same timestamp and dimensions aren't grouped into the same document, ES will consider them to be a duplicate. The _metric_names_hash field will be set by the OTel ES exporter. As it's mapped as a time_series_dimensions, it creates a different _tsid for documents with different sets of metrics. The tradeoff is that if the composition of the metrics grouping changes over time, a different _tsid will be created. That has an impact on the rate aggregation for counters.
felixbarny
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:Data Management/Data streams
elasticsearchmachine
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Pinging @elastic/es-data-management (Team:Data Management) |
elasticsearchmachine
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Hi @felixbarny, I've created a changelog YAML for you. |
carsonip
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Jan 27, 2025
| @@ -14,6 +14,10 @@ template: | |||
| type: passthrough | |||
| dynamic: true | |||
| priority: 10 | |||
| # workaround for https://github.com/elastic/elasticsearch/issues/99123 | |||
| _metric_names_hash: | |||
| type: keyword | |||
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Q: will a number be more lightweight, as you're using a 8 digit hex anyway?
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At the moment, numbers can't leverage run-length encoding. So it's actually lighter to use a keyword here as all dimensions are incorporated into the _tsid, which we sort by. Therefore, all values for the same tsid are equal and can be compressed very efficiently.
carsonip
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Jan 28, 2025
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A short-term workaround for #99123
If metrics that have the same timestamp and dimensions aren't grouped into the same document, ES will consider them to be a duplicate. The
_metric_names_hashfield will be set by the OTel ES exporter (see open-telemetry/opentelemetry-collector-contrib#37511). As it's mapped as a time_series_dimensions, it creates a different _tsid for documents with different sets of metrics. The tradeoff is that if the composition of the metrics grouping changes over time, a different _tsid will be created. That has an impact on the rate aggregation for counters.