Return big amount of values without paging

[ivgenik]

Hello,
Lets say I got an index with a big amount of documents.
Each one has a field called UniqueId.
I need to create a query with a simple filter and return all of the uniqueIds that answers the query.
The data looks like:

My document:
{
...
DocNum: 123,
UniqueId: 232-32321-1
...
}

I read that in terms of response size it is not recommended to go over 10,000 records?
Is it also true if I cut my response to only contain this 1 field inside each _source? of the 10,000++ responses?

So that the response will look like :
"hits": [
{
"_index": "",
"_type": "_doc",
"_id": "",
"_score": null,
"_source": {
"UniqueId": 232-32321-1
}}

If it is a problem can it be solved by aggregating the result of the uniqueIds instead? or will it result in having the same "max" size problem?

P.S.
Sadly I cant use paging for this.

[ivgenik]

I ended up using the _source option as mentioned to return only one field.
The default max size seem to be 30,000 now.
My case should be pretty rare and I think it answers my current needs since the relevant query should not hit anywhere near 30,000 values.