Question

I’m using elasticsearch to index my documents.

Is it possible to instruct it to only return particular fields instead of the entire json document it has stored?

Answer 1

Yep, Use a better option source filter. If you’re searching with JSON it’ll look something like this:

{
    "_source": ["user", "message", ...],
    "query": ...,
    "size": ...
}

In ES 2.4 and earlier, you could also use the fields option to the search API:

{
    "fields": ["user", "message", ...],
    "query": ...,
    "size": ...
}

This is deprecated in ES 5+. And source filters are more powerful anyway!