Elasticsearch Error: Field data circuit breaker tripped - Common Causes & Fixes

Brief Explanation

The "Field data circuit breaker tripped" error in Elasticsearch occurs when the field data circuit breaker is triggered. This happens when the estimated memory usage for loading field data exceeds the configured limit, preventing potential out-of-memory errors.

Impact

This error can significantly impact query performance and cluster stability. When the circuit breaker trips, it prevents the loading of field data for certain queries, which can lead to query failures or incomplete results. In severe cases, it may cause node instability or cluster-wide issues if not addressed promptly.

Common Causes

1. Insufficient memory allocation for field data
2. Queries involving large text fields with many unique terms
3. Improper mapping of fields (e.g., using text instead of keyword for non-analyzed fields)
4. Aggregations on high-cardinality fields
5. Outdated Elasticsearch version with known memory management issues

Troubleshooting and Resolution Steps

1. Check the current circuit breaker settings:

   GET /_nodes/stats/breaker
   

2. Increase the field data circuit breaker limit if necessary:

   PUT /_cluster/settings
   {
     "persistent": {
       "indices.breaker.fielddata.limit": "60%"
     }
   }
   

3. Optimize your mappings:

   • Use keyword type for fields that don't need to be analyzed
   • Apply doc_values: false for fields that don't require sorting or aggregations

4. Implement pagination for large result sets

5. Use filter aggregations instead of terms aggregations for high-cardinality fields

6. Consider using the composite aggregation for more efficient memory usage

7. Upgrade to the latest Elasticsearch version if you're running an older version

Best Practices

1. Regularly monitor circuit breaker statistics
2. Implement proper capacity planning and scaling strategies
3. Use appropriate field types and mappings
4. Optimize queries and aggregations for better performance
5. Consider using doc values instead of field data when possible

Frequently Asked Questions

Q: What is the default limit for the field data circuit breaker?
A: The default limit is 40% of the JVM heap size.

Q: Can increasing the circuit breaker limit solve all field data issues?
A: While increasing the limit can provide temporary relief, it's not a long-term solution. It's important to address the root cause by optimizing mappings, queries, and aggregations.

Q: How does the field data circuit breaker differ from other circuit breakers in Elasticsearch?
A: The field data circuit breaker specifically monitors memory usage for field data loading, while other circuit breakers (like request and parent) focus on different aspects of memory usage in Elasticsearch.

Q: Can the field data circuit breaker be disabled?
A: It is not recommended to disable the field data circuit breaker as it protects against out-of-memory errors. However, you can set a very high limit if absolutely necessary.

Q: How can I identify which queries or fields are causing the circuit breaker to trip?
A: You can use the Elasticsearch slow log to identify problematic queries and the _nodes/stats/indices/fielddata API to see which fields are consuming the most field data memory.