Elasticsearch: Difference between "Term", "Match Phrase", and "Query String"

Question

New here to Elasticsearch and trying to get a better understanding on the difference between these queries. As far as I can tell, term matches a single term (needs to be lowercase for the match to work?), and both match phrase and query string matches a string of text.

Answer 1

term query matches a single term as it is : the value is not analyzed. So, it doesn't have to be lowercased depending on what you have indexed.

If you provided Bennett at index time and the value is not analyzed, the following query won't return anything :

{
  "query": {
    "term" : { "user" : "bennett" }
  }
}

match_phrase query will analyze the input if analyzers are defined for the queried field and find documents matching the following criterias :

• all the terms must appear in the field
• they must have the same order as the input value

For example, if you index the following documents (using standard analyzer for the field foo):

{ "foo":"I just said hello world" }

{ "foo":"Hello world" }

{ "foo":"World Hello" }

This match_phrase query will only return the first and second documents :

{
  "query": {
    "match_phrase": {
      "foo": "Hello World"
    }
  }
}

query_string query search, by default, on a _all field which contains the text of several text fields at once. On top of that, it's parsed and supports some operators (AND/OR...), wildcards and so on (see related syntax).

As the match_phrase queries, the input is analyzed according to the analyzer set on the queried field.

Unlike the match_phrase, the terms obtained after analysis don't have to be in the same order, unless the user has used quotes around the input.

For example, using the same documents as before, this query will return all the documents :

{
  "query": {
    "query_string": {
      "query": "hello World"
    }
  }
}

But this query will return the same 2 documents as the match_phrase query :

{
  "query": {
    "query_string": {
      "query": "\"Hello World\""
    }
  }
}

There is much more to say about the different options for those queries, please take a look at the related documentation :

• term
• match_phrase
• query_string

Hope this is clear enough and it will help.