Nested, join multiple indexes

Elastic Stack Elasticsearch
1

Hello, I've some difficulties to understand how works "join alternative, nested, object type, ..." in ES.
I've read some docs (like Nested field type | Elasticsearch Guide [8.11] | Elastic) but I can't see how a nested object is mapped to another indice.

index xxx_* - { "key":"value", "ip" : "value"}
index abcd - { "ip":"value", "name":"value", "desc":"value"}

I wish to join xxx_*.ip with abcd.ip.

Someone can explain me how to do that ?

Thank for your help.

2

You can not join across indices in Elasticsearch. You can represent some types of relationships using parent-child mappings or nested documents, but this requires data to be in a single index and is not a join. It is generally recommended to not try an think about your data in relational terms and instead denormalize data into a structure that suits how you want to search or aggregate it.