I want to know why the indices.id_field_data.enabled configuration is turned off by default

[Kurt_Rudolph]

This topic got automatically closed without an answer I want to know why the indices.id_field_data.enabled configuration is turned off by default

I'm evaluating the impacts of upgrading from v7 -> v8 and found an issue with indices.id_field_data.enabled now not enabled by default. In v7 it is, in v8 it's not. Why ?

I can't actually find specific doc for this configuration. I can somewhat infer what it does based on the doc for the fielddata setting on the mapping Text type family | Elasticsearch Guide [8.9] | Elastic and assume it's because it can use significant memory but also I could be totally off and could use some explanation from the elastic folks.

[leandrojmp (Leandro Pereira)]

Sorting and aggregate on the _id field was deprecated on 7.6 and disabled by default on version 8 as you alredy found out.

This is mentioned in the breaking changes.

Fielddata is pretty expensive as it will use reside on the heap memory as mentioned in the documentation.

The main reason to disable this is probably this github issue with more explanation about the impacts.