Elasticsearch - Search APIs - Adglob Infosystem Pvt Ltd

These Elasticsearch Search APIs are used to search content in Elasticsearch. A user can search by sending a get request with a query string as a parameter or they can post a query in the message body of the post request. Mainly all the search APIS are multi-index, multi-type.

Elasticsearch Search APIs In Multi-Index

Elasticsearch allows us to search for the documents present in all the indices or in some specific indices. For example, if we need to search all the documents with a name that contains central, we can do as shown here −

GET /_all/_search?q=city:paprola

On running the above code, we get the following response −

{
   "took" : 33,
   "timed_out" : false,
   "_shards" : {
      "total" : 7,
      "successful" : 7,
      "skipped" : 0,
      "failed" : 0
   },
   "hits" : {
      "total" : {
         "value" : 1,
         "relation" : "eq"
      },
      "max_score" : 0.9808292,
      "hits" : [
         {
            "_index" : "schools",
            "_type" : "school",
            "_id" : "5",
            "_score" : 0.9808292,
            "_source" : {
               "name" : "Central School",
               "description" : "CBSE Affiliation",
               "street" : "Nagan",
               "city" : "paprola",
               "state" : "HP",
               "zip" : "176115",
               "location" : [
                  31.8955385,
                  76.8380405
               ],
               "fees" : 2200,
               "tags" : [
                  "Senior Secondary",
                  "beautiful campus"
               ],
               "rating" : "3.3"
            }
         }
      ]
   }
}

URI Search

Many parameters can be passed in a search operation using Uniform Resource Identifier −

S.No	Parameter & Description
1	Q This parameter is used to specify query string.
2	lenient This parameter is used to specify query string. Format-based errors can be ignored by just setting this parameter to true. It is false by default.
3	fieldsThis parameters is used to specify query string.
4	sortWe can get sorted result by using this parameter, the possible values for this parameter is fieldName, fieldName:asc/field name:desc
5	the timeout can restrict the search time by using this parameter and the response only contains the hits in that specified time. By default, there is no timeout.
6	terminate_afterWe can restrict the response to a specified number of documents for each shard, upon reaching which the query will terminate early. By default, there is no terminate_after.
7	fromThe starting from the index of the hits to return. Defaults to 0.
8	sizeIt denotes the number of hits to return. Defaults to 10.

Request Body Search

We can also specify a query using query DSL in the request body and there are many examples already given in previous chapters. One such example is given here −

POST /schools/_search
{
   "query":{
      "query_string":{
         "query":"up"
      }
   }
}

On running the above code, we get the following response −

{
   "took" : 11,
   "timed_out" : false,
   "_shards" : {
      "total" : 1,
      "successful" : 1,
      "skipped" : 0,
      "failed" : 0
   },
   "hits" : {
      "total" : {
         "value" : 1,
         "relation" : "eq"
      },
      "max_score" : 0.47000363,
      "hits" : [
         {
            "_index" : "schools",
            "_type" : "school",
            "_id" : "4",
            "_score" : 0.47000363,
            "_source" : {
               "name" : "City Best School",
               "description" : "ICSE",
               "street" : "West End",
               "city" : "Meerut",
               "state" : "UP",
               "zip" : "250002",
               "location" : [
                  28.9926174,
                  77.692485
               ],
               "fees" : 3500,
               "tags" : [
                  "fully computerized"
               ],
               "rating" : "4.5"
            }
         }
      ]
   }
}

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