Java API client - single metric aggregation zero or null deserializer

Elastic Stack Elasticsearch
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I am using elasticsearch-java api client (8.10.3) and facing a small issue and I hope someone has already encountered this issue before.

I am trying to perform a min aggregation on documents that may not contain the field I try to aggregate. In case that all the documents that match my query don't contain the field I try to aggregate, the "value": null is being deserializing to 0 via the JsonpDeserializer.doubleOrNullDeserializer(0) which is defined inside the setupSingleMetricAggregateBaseDeserializer SingleMetricAggregateBase class

In my opinion, this approach may lead to confusion in our product and I am searching a way to avoid this deserialization but I couldn't find so far. It's ok to return null in that case and I would prefer to achieve this.

any ideas? :slight_smile:

I tried to add also value count aggregation in order to determine if there are values in the field I try to aggregate and it worked but it is a little weird in my opinion.

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Hello!
The Java client defaults to zero when deserializing aggregation results because of a design choice that was made in order to avoid boxing numbers, which could increase memory usage substantially.
Using the document count provided in the response to make sure that the 0 returned is a "real zero" is a valid approach, and in general since modifying this behaviour would be a breaking change we would prefer to keep it as is for now.

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Update: from version 9.0.0 of the Java client, the result of aggregations has been changed so that it reflects exactly what the elasticsearch server sends, so if the server returns null, it will be deserialized and returned as null by the Java client.