Reverse nested nested path path is not nested – How to solve this OpenSearch exception

Opster Team

Aug-23, Version: 1-2.9

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Briefly, this error occurs when OpenSearch tries to execute a reverse nested aggregation on a field that is not nested. This means that the field you’re trying to aggregate is not within a nested data type. To resolve this issue, you can either change your query to target a nested field, or modify your index mapping to make the target field nested. Additionally, ensure that the path specified in the reverse nested aggregation is correct and refers to a nested field.

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This guide will help you check for common problems that cause the log ” [reverse_nested] nested path [” + path + “] is not nested ” to appear. To understand the issues related to this log, read the explanation below about the following OpenSearch concepts: aggregations, search.

Log Context

Log “[reverse_nested] nested path [” + path + “] is not nested” class name is We extracted the following from OpenSearch source code for those seeking an in-depth context :

 parentObjectMapper = queryShardContext.getObjectMapper(path);
 if (parentObjectMapper == null) {
 return new ReverseNestedAggregatorFactory(name; true; null; queryShardContext; parent; subFactoriesBuilder; metadata);
 if (parentObjectMapper.nested().isNested() == false) {
 throw new AggregationExecutionException("[reverse_nested] nested path [" + path + "] is not nested");
 }  NestedScope nestedScope = queryShardContext.nestedScope();
 try {


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