DSL debugging information

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Verify Queries

Queries can become very complex, especially after the combination of different analyzers and field mapping, will be some difficulty.

validate API can verify that a query is legitimate.

GET /gb/tweet/_validate/query
{
   "query": {
      "tweet" : {
         "match" : "really powerful"
      }
   }
}

Above the return value of the request told us that this statement is illegal:

{
  "valid" :         false,
  "_shards" : {
    "total" :       1,
    "successful" :  1,
    "failed" :      0
  }
}

Understanding Error Messages

Want to know the specific statement is illegal error message, you need to add  explain parameters:

GET /gb/tweet/_validate/query?explain <1>
{
   "query": {
      "tweet" : {
         "match" : "really powerful"
      }
   }
}

<1>  explain parameters can provide more details wrong statement.

Obviously, we query statement  match with the location of the field name backwards:

{
  "valid" :     false,
  "_shards" :   { ... },
  "explanations" : [ {
    "index" :   "gb",
    "valid" :   false,
    "error" :   "org.elasticsearch.index.query.QueryParsingException:
                 [gb] No query registered for [tweet]"
  } ]
}

Understanding query

If this is a legitimate statement, use  explain parameter may be returned with a reading of the description of the query, the query can help us understand how the ES is executed:

GET /_validate/query?explain
{
   "query": {
      "match" : {
         "tweet" : "really powerful"
      }
   }
}

explanation It returns a description for each index, because each index will have different mapping relationships and Analyzer:

{
  "valid" :         true,
  "_shards" :       { ... },
  "explanations" : [ {
    "index" :       "us",
    "valid" :       true,
    "explanation" : "tweet:really tweet:powerful"
  }, {
    "index" :       "gb",
    "valid" :       true,
    "explanation" : "tweet:really tweet:power"
  } ]
}

From return  explanation you will see  match how the query string for the  "really powerful" query, first of all, it split into two separate words are in the  tweet query field.

Further, the index usin the two terms "really"and "powerful", in the index gbare split into "really" and  "power". This is because we in the index gbused in the englishanalyzer.

Reproduced in: https: //my.oschina.net/fusublog/blog/3057672