cannot search doc with key field start with "_"
I have below doc, when I search doc by url: http://localhost:9200/indexName/_search?q=hanoi
It return empty doc
{
"company": "software",
"_quantity":500,
"company_location":"vietnam",
"_city":"hanoi"
}
Could anyone explain why it happens? and send me link about rule of field name in elasticsearch
Note: I still can search doc by field name start other character