type keyword and not analyzed, any difference?

Question

Is there any difference between the "keyword" field type and a field that uses "not_analyzed" as analyzer in Elasticsearch? If there is one, when to use which?

Answer 1

As can be seen in the breaking changes documentation, the keyword data type is a new data type coming up in ES 5. It aims at replacing the string fields with "index": "not_analyzed".

So in ES 1.x and 2.x, this declaration

"field": {
    "type": "string",
    "index": "not_analyzed"
}

is equivalent to this declaration in ES 5

"field": {
    "type": "keyword"
}

Similarly, the text data type will replace normal analyzed string fields, so in ES 1.x and 2.x, this declaration

"field": {
    "type": "string"
}

will equivalent to this declaration in ES 5

"field": {
    "type": "text"
}