Can nested fields prevent mapping explosion?

Elastic Stack Elasticsearch
2

Unfortunately, it won't help. Nested documents all share the same "mapping space" of the index, which means you'll have the same limitations. Under the covers, nested documents are really just regular documents that adhere to some special, hidden conventions which allow them to be used with relational Nested queries.

So they contribute to the field-count for the index they reside in, just like fields on "regular" documents. Sorry :confused:

What most people do is a key/value situation like the linked article in your other thread. This makes use of nested fields, but only adds a few fields to the total mapping:

{
  "values" :[
    {"key": 1, "value": 1}
    {"key": 2, "value": 4}
    {"key": 3, "value": 9}
    {"key": 4, "value": 16}
    {"key": 5, "value": 25}
    {"key": 6, "value": 36}
  ]
}

In the above example, there are only three fields mapped ("values", "key", "value"), and the nested structure allows each key/value to be associated together. It's a lot less easy to work with then direct mapping, but pretty much the only option if you expect to have thousands of distinct fields.

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