Java API client - single metric aggregation zero or null deserializer

Almog_Oz · March 26, 2024, 8:18pm

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

github.com

elastic/elasticsearch-java/blob/main/java-client/src/main/java/co/elastic/clients/elasticsearch/_types/aggregations/SingleMetricAggregateBase.java

/*
 * Licensed to Elasticsearch B.V. under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch B.V. licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package co.elastic.clients.elasticsearch._types.aggregations;

This file has been truncated. show original

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?

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.

ltrotta · April 2, 2024, 2:28pm

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.

system · April 30, 2024, 2:29pm

This topic was automatically closed 28 days after the last reply. New replies are no longer allowed.