QueryString query - quoted _exists_ query returns no result

[nikoncode]

Elasticsearch version (bin/elasticsearch --version): 6.2.1

Plugins installed: []

JVM version (java -version): OpenJDK Runtime Environment (build 1.8.0_162-b01)

OS version (uname -a if on a Unix-like system): Linux mikita-pc 4.14.20-2-MANJARO #1 SMP PREEMPT Sat Feb 17 21:47:27 CET 2018 x86_64 GNU/Linux

Description of the problem including expected versus actual behavior:
_exists_: test - works (converted in NormsFieldExistsQuery),
_exists_: \"test\" - doesn't work (converted in MatchNoDocsQuery("unmapped field [_exists_]")).
It's not possible to use _exists_ in query_string query with fields which contains spaces in name (it works in es 1.7)

Steps to reproduce:

POST localhost:9200/tests/test/1
{
	"name": "aa"
}

POST localhost:9200/tests/test/_search (returns document, expected)
{
   "query":{
      "query_string":{
         "query":"_exists_: name"
      }
   }
}

POST localhost:9200/tests/test/_search (returns nothing, not expected but works in ES 1.7)
{
   "query":{
      "query_string":{
         "query":"_exists_: \"name\""
      }
   }
}

It's impossible to use exists query with field with spaces:

POST localhost:9200/tests/test/1
{
	"na me": "aa"
}

POST localhost:9200/tests/test/_search (returns nothing, expected)
{
   "query":{
      "query_string":{
         "query":"_exists_: na me"
      }
   }
}

POST localhost:9200/tests/test/_search (returns nothing, not expected, works in ES 1.7)
{
   "query":{
      "query_string":{
         "query":"_exists_: \"na me\""
      }
   }
}

[spinscale]

@elastic/es-search-aggs can you take a look?

One can use "query":"_exists_:na\\ me" to get the desired result, though I am not sure if the above syntax is expected to work as well

[jimczi]

This is a regression, we should accept the quoted version (e.g. _exists_:"na me"). I'll work on a fix.

[nikoncode]

@jimczi since no progress on this issue, would you mind if I try to fix it by myself?

[jimczi]

Sorry for the delay @nikoncode , this issue slipped through the cracks. I opened #33019 to fix it.