How to use join on elasticsearch

Question

Imagine that I have some elasticsearch indexes. I'm fetching them via a key. For example, that key is a city. As an example, fetching all users date from Maribor. My aim is fetching users from maribor and get user's event date and fetching from Ljubljana and get same user's event date and compare them. How can i do this ? For being clear, it is same with join method in traditional db. I already checked aggregations but i couldn't solve it. Can someone give an example of query dsl ?

As a scenario,

{
    "username" : "marko"
    "city" : "maribor"
    "event-date": "22-02-2020"
    "another-city" : "empty"
    ....
}

{
    "username" : "marko"
    "city" : "ljubljana"
    "event-date": "22-02-2020"
    "another-city" : "empty"
    ....
}

{
    "username" : "slvia"
    "city" : "ljubljana"
    "event-date": "22-02-2020"
    ....
}

I want to fetch only username is "marko" and city "ljubljana" or "maribor" and event-date "22-02-2020". If username = "marko" city "ljubljana" set anothercity second one's city. I mean set "another-city": maribor, else if username = "marko" city "maribor" set anothercity first one's. I mean set "another-city" : ljubljana. Likewise cross match data

Thanks for answering

Answer 1

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