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Important: This documentation is about an older version. It's relevant only to the release noted, many of the features and functions have been updated or replaced. Please view the current version.

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Tag search

An issue occurs while searching for traces in Grafana Explore. The Service Name and Span Name drop down lists are empty, and there is a No options found message.

HTTP requests to Tempo query frontend endpoint at /api/search/tag/service.name/values would respond with an empty set.

Root cause

The introduction of a cap on the size of tags causes this issue.

Configuration parameter max_bytes_per_tag_values_query causes the return of an empty result when a query exceeds the configured value.

Solutions

There are two main solutions to this issue:

  • Reduce the cardinality of tags pushed to Tempo. Reducing the number of unique tag values will reduce the size returned by a tag search query.
  • Increase the max_bytes_per_tag_values_query parameter in the overrides block of your Tempo configuration to a value as high as 50MB.