Support match_phrase function in SQL/PPL query engine

[chloe-zh]

Related design is presented in issue #182

Todo list

• Support the match_phrase functionality by pushing it down to the search engine
• Enable match_phrase function in SQL and PPL syntax and parser, including all the available parameters
• Make sure the function in new engine is compatible with the old engine support (including match_phrase and matchphrase functions in old engine)
• Add unit tests. (Unit tests are mandatory for all code changes.)
• Add integration test cases for match_phrase
• Update user manual

Function details

The match_phrase function maps to the match phrase query used in search engine. This query analyzes the text and creates a phrase query out of the analyzed text.

Syntax:
match_phrase(field_expression, query_expression[, option=<option_value>]*)

Available options:

• analyzer
• zero_terms_query

Sample queries:

# Search query 1
GET my_index/_search
{
  "query": {
    "match_phrase": {
      "message": "this is a test"
    }
  }
}

# SQL
SELECT * FROM my_index WHERE match_phrase(message, "this is a test")

# PPL 
source=my_index | match type=match_phrase field=message query="this is a test"


# Search query 2
GET my_index/_search
{
  "query": {
    "match_phrase": {
      "message": {
        "query": "this is a test",
        "analyzer": "my_analyzer"
      }
    }
  }
}

# SQL
SELECT* FROM my_index WHERE match_phrase(message, "this is a test", analyzer="my_analyzer") 

# PPL 
source=my_index | where match_phrase(message, "this is a test", analyzer="my_analyzer")

[MaxKsyunz]

@penghuo, should the PPL parser support alternative spelling of match_phrase like matchphrase?

For example, are queries like source=index | where matchphrase(field, 'text') valid?

[joshuali925]

@MaxKsyunz match_pharse should be enough, i don't think PPL functions support alternative spellings (there is date_format() but not dateformat())

[MaxKsyunz]

@joshuali925, here's a demo of the changes in PR #604

match_phrase.demo-web.mp4

[acarbonetto]

fixed by: #604