Fields not searchable with subobjects: false and dynamic: false when sent as nested objects

[flash1293]

Elasticsearch Version

main

Installed Plugins

No response

Java Version

bundled

OS Version

Darwin Mac 24.1.0

Problem Description

When subobjects: false and dynamic: false are used together in an index, fields are not searchable if the documents are sent as nested objects.

Steps to Reproduce

Prepare:

PUT my-index
{
  "mappings": {
    "subobjects": false,
    "dynamic": false,
    "properties": {
      "my.keyword.field": {
        "type": "keyword"
      }
    }
  }
}

POST my-index/_doc
{
  "my": {
    "keyword.field": "abc"
  }
}

GET my-index*/_search
{
  "fields": [
    "*"
  ]
}

Returns

        "fields": {
          "my.keyword.field": [
            "abc"
          ]
        }

so it looks like my.keyword.field is indexed properly.

However,

GET my-index/_search
{
  "query": {
    "match": {
      "my.keyword.field": "abc"
    }
  }
}

does not return any hits.

• When setting dynamic: true, the match-search works as expected (even though the mapping looks exactly the same)
• When setting subobjects: true, the match-search works as expected
• When sending the doc as { "my.keyword.field": "abc" }, the match-search works as expected

Logs (if relevant)

No response

[flash1293]

cc @martijnvg - maybe you have an idea

[elasticsearchmachine]

Pinging @elastic/es-storage-engine (Team:StorageEngine)

[lkts]

The result of fields parameter is misleading here, not sure why. There is no field my.keyword.field in Lucene document in this case. I think that object auto-flattening indirectly depends on dynamic updates somehow causing this bug.