[入門] Elasticsearchとは？概要から使い方までわかりやすく解説

version: '3'
services:
  elasticsearch:
    image: elasticsearch:7.12.1
    container_name: elasticsearch
    environment:
      - discovery.type=single-node
    ports:
      - 9200:9200
  kibana:
    image: kibana:7.12.1
    ports:
      - "5601:5601"
    environment:
      - ELASTICSEARCH_HOSTS=http://elasticsearch:9200

PUT /test/_doc/1
{
  "date":"2020/11/01 09:00 JST",
  "Tweet":"ツイッターをはじめました。",
  "User ID":"hoge"
}

{
  (中略)
  "_source" : {
    "date" : "2020/11/01 09:00 JST",
    "Tweet" : "ツイッターをはじめました。",
    "User ID" : "hoge"
  }
}

POST /test/_update/1
{
  "doc": {
    "Tweet":"フィールドを更新したよ。"
  }
}

PUT /test/_doc/1
{
  "Tweet":"ドキュメントを置き換えたよ"
}

  "_version" : 3,
  "_source" : {
    "Tweet" : "ドキュメントを置き換えたよ"
  }

{
  "_index" : "test",
  "_type" : "_doc",
  "_id" : "1",
  "found" : false
}

POST /_bulk
{ "index" : { "_index" : "test", "_id" : "1" } }
{ "フィールドのキー" : "フィールドの値を置き換え" }
{ "delete" : { "_index" : "test", "_id" : "2" } }
{ "create" : { "_index" : "test", "_id" : "3" } }
{ "フィールドのキー" : "フィールドの値を作成" }
{ "update" : { "_index" : "test", "_id" : "3" } }
{ "doc" : {"フィールドのキー" : "フィールドの値を更新"} }

GET /test/_search

      {
        "_index": "test",
        "_id": "3",
        "_score": 1,
        "_source": {
          "フィールドのキー": "フィールドの値を更新"
        }
      },
      {
        "_index": "test",
        "_id": "1",
        "_score": 1,
        "_source": {
          "フィールドのキー": "フィールドの値を置き換え"
        }
      }

POST /_bulk
{ "index" : { "_index" : "demo_search", "_id" : "1" } }
{ "text" : "This is Elasticsearch test.", "num" : 1 }
{ "index" : { "_index" : "demo_search", "_id" : "2" } }
{ "text" : "Elasticsearch is search engine.", "num" : 2 }
{ "index" : { "_index" : "demo_search", "_id" : "3" } }
{ "text" : "This is a pen.", "num" : 3 }

GET /demo_search/_search
{
  "query":{
    "match": {
      "text" : "engine"
    } 
  }
}

(中略)
        "_source": {
          "text": "Elasticsearch is search engine."

GET /demo_search/_search
{
  "query":{
    "match": {
      "text": {
        "query": "Elasticsearch engine",
        "operator":"AND"
      }
    } 
  }
}

(中略)
        "_source" : {
          "text" : "Elasticsearch is search engine."

GET /demo_search/_search
{
  "query":{
    "match_phrase": {
      "text": "Elasticsearch test"
    } 
  }
}

GET /demo_search/_search
{
  "query":{
    "term": {
      "text.keyword": "This is Elasticsearch test."
    } 
  }
}

        "_source" : {
          "text" : "This is Elasticsearch test."

GET /demo_search/_search
{
  "query":{
    "terms": {
      "text.keyword":["This is Elasticsearch test.","This is a pen."]
    } 
  }
}

"_source" : {
          "text" : "This is Elasticsearch test."
        }
        (中略)
        "_source" : {
          "text" : "This is a pen."
        }

GET /demo_search/_search
{
  "query":{
    "wildcard": {
      "text" : "eng*"
    } 
  }
}

        "_source": {
          "text": "Elasticsearch is search engine.",
          "num": 2
        }

GET /demo_search/_search
{
  "query":{
    "range": {
      "num":{
        "gte": "1",
        "lte": "2"
      }
    } 
  }
}

    "hits" : [
      {
        "_index" : "demo_search",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 1.0,
        "_source" : {
          "text" : "This is Elasticsearch test.",
          "num" : 1
        }
      },
      {
        "_index" : "demo_search",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "text" : "Elasticsearch is search engine.",
          "num" : 2
        }
      }

GET /demo_search/_search
{
  "query":{
    "bool": {
      "must":[
        {"match":{"text":"Elasticsearch"}},
        {"range":{"num":{"lte":"1"}}}
      ]
    } 
  }
}

        "_source" : {
          "text" : "This is Elasticsearch test.",
          "num" : 1
        }

GET /demo_search/_search
{
  "query":{
    "bool": {
      "should":[
        {"match":{"text":"engine"}},
        {"range":{"num":{"gte":"2"}}}
      ]
    } 
  }
}

      {
        "_index": "demo_search",
        "_id": "2",
        "_score": 1.287682,
        "_source": {
          "text": "Elasticsearch is search engine.",
          "num": 2
        }
      },
      {
        "_index": "demo_search",
        "_id": "3",
        "_score": 1,
        "_source": {
          "text": "This is a pen.",
          "num": 3
        }
      }

GET /demo_search/_search
{
  "query":{
    "bool": {
      "must_not":[
        {"match":{"text":"Elasticsearch"}}
      ]
    } 
  }
}

    "hits" : [
      {
        "_index" : "demo_search",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 0.0,
        "_source" : {
          "text" : "This is a pen.",
          "num" : 3
        }
      }

GET /demo_search/_search
{
  "query":{
    "bool": {
      "must": [
        {"match":{"text":"Elasticsearch"}}
      ], 
      "filter":[
        {"range":{"num":{"lte":"1"}}}
      ]
    } 
  }
}

        "_source" : {
          "text" : "This is Elasticsearch test.",
          "num" : 1
        }

POST /_bulk
{ "index" : { "_index" : "demo_agg", "_id" : "1" } }
{ "text" : "This is Elasticsearch test.", "num" : 1 }
{ "index" : { "_index" : "demo_agg", "_id" : "2" } }
{ "text" : "Elasticsearch is search engine.", "num" : 2 }
{ "index" : { "_index" : "demo_agg", "_id" : "3" } }
{ "text" : "This is a pen.", "num" : 3 }

GET demo_agg/_search
{
  "size": 0,
  "aggs": {
    "集計の名前": {
      "avg": {
        "field":"num"
      }
    }
  }
}

  "aggregations" : {
    "集計の名前" : {
      "value" : 2.0
    }
  }

GET demo_agg/_search
{
  "size": 0,
  "aggs": {
    "バケットの名前": {
      "range": {
        "field":"num",
        "ranges": [
          {
            "from": 0,
            "to":2
          },
          {
            "from": 2
          }
        ]
      }
    }
  }
}

  "aggregations" : {
    "バケットの名前" : {
      "buckets" : [
        {
          "key" : "0.0-2.0",
          "from" : 0.0,
          "to" : 2.0,
          "doc_count" : 1
        },
        {
          "key" : "2.0-*",
          "from" : 2.0,
          "doc_count" : 3
        }
      ]
    }

GET demo_agg/_search
{
  "size": 0,
  "aggs": {
    "バケットの名前": {
      "histogram": {
        "field":"num",
        "interval": 1
      }
    }
  }
}

  "aggregations" : {
    "バケットの名前" : {
      "buckets" : [
        {
          "key" : 1.0,
          "doc_count" : 1
        },
        {
          "key" : 2.0,
          "doc_count" : 2
        },
        {
          "key" : 3.0,
          "doc_count" : 1
        }
      ]

POST /demo_agg/_search
{
  "size": 0,
  "aggs": {
    "１段目の名前": {
      "range": {
        "field": "num",
        "ranges": [
          {
            "from": 1,
            "to":2
          },
          {
            "from": 2
          }
        ]
      },
      "aggs": {
        "2段目の名前": {
          "sum": {
            "field": "num"
          }
        }
      }
    }
  }
}

    "１段目の名前": {
      "buckets": [
        {
          "key": "1.0-2.0",
          "from": 1,
          "to": 2,
          "doc_count": 1,
          "2段目の名前": {
            "value": 1
          }
        },
        {
          "key": "2.0-*",
          "from": 2,
          "doc_count": 2,
          "2段目の名前": {
            "value": 5