Elasticsearch学习笔记——安装、数据导入和查询

到elasticsearch网站下载最新版本的elasticsearch 6.2.1

https://www.elastic.co/downloads/elasticsearch

中文文档请参考

https://www.elastic.co/guide/cn/elasticsearch/guide/current/index.html

英文文档及其Java API使用方法请参考，官方文档比任何博客均可信

https://www.elastic.co/guide/en/elasticsearch/client/java-api/current/index.html

Python API使用方法

http://elasticsearch-py.readthedocs.io/en/master/

下载tar包，而后解压到/usr/local目录下，修改一下用户和组以后能够使用非root用户启动，启动命令

./bin/elasticsearch

而后访问http://127.0.0.1:9200/

若是须要让外网访问Elasticsearch的9200端口的话，须要将es的host绑定到外网

修改 /configs/elasticsearch.yml文件，添加以下

network.host: 0.0.0.0
http.port: 9200

而后重启，若是遇到下面问题的话

[2018-01-28T23:51:35,204][INFO ][o.e.b.BootstrapChecks    ] [qR5cyzh] bound or publishing to a non-loopback address, enforcing bootstrap checks
ERROR: [2] bootstrap checks failed
[1]: max file descriptors [4096] for elasticsearch process is too low, increase to at least [65536]
[2]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]

解决方法

在root用户下执行

sysctl -w vm.max_map_count=262144

 

接下来导入json格式的数据，数据内容以下

{"index":{"_id":"1"}}
{"title":"许宝江","url":"7254863","chineseName":"许宝江","sex":"男","occupation":" 滦县农业局局长","nationality":"中国"}
{"index":{"_id":"2"}}
{"title":"鲍志成","url":"2074015","chineseName":"鲍志成","occupation":"医师","nationality":"中国","birthDate":"1901年","deathDate":"1973年","graduatedFrom":"香港大学"}

 须要注意的是{"index":{"_id":"1"}}和文件末尾另起一行换行是不可少的

其中的id能够从0开始，甚至是abc等等

不然会出现400状态，错误提示分别为

Malformed action/metadata line [1], expected START_OBJECT or END_OBJECT but found [VALUE_STRING]

The bulk request must be terminated by a newline [\n]"

使用下面命令来导入json文件

其中的people.json为文件的路径，能够是/home/common/下载/xxx.json

其中的es是index，people是type，在elasticsearch中的index和type能够理解成关系数据库中的database和table，二者都是必不可少的

curl -H "Content-Type: application/json" -XPOST 'localhost:9200/es/people/_bulk?pretty&refresh' --data-binary "@people.json"

 成功后的返回值是200，好比

{
  "took" : 233,
  "errors" : false,
  "items" : [
    {
      "index" : {
        "_index" : "es",
        "_type" : "people",
        "_id" : "1",
        "_version" : 1,
        "result" : "created",
        "forced_refresh" : true,
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 0,
        "_primary_term" : 1,
        "status" : 201
      }
    },
    {
      "index" : {
        "_index" : "es",
        "_type" : "people",
        "_id" : "2",
        "_version" : 1,
        "result" : "created",
        "forced_refresh" : true,
        "_shards" : {
          "total" : 2,
          "successful" : 1,
          "failed" : 0
        },
        "_seq_no" : 0,
        "_primary_term" : 1,
        "status" : 201
      }
    }
  ]
}

<0>查看字段的mapping

http://localhost:9200/es/people/_mapping

 

 

 接下来能够使用对应的查询语句对数据进行查询

 <1>按id来查询

http://localhost:9200/es/people/1

 

<2>简单的匹配查询，查询某个字段中包含某个关键字的数据（GET）

http://localhost:9200/es/people/_search?q=_id:1

http://localhost:9200/es/people/_search?q=title:许

 

<3>多字段查询，在多个字段中查询包含某个关键字的数据（POST）

能够使用Firefox中的RESTer插件来构造一个POST请求，在升级到Firefox quantum以后，原来使用的Poster插件挂了

在title和sex字段中查询包含 许 字的数据

{
    "query": {
        "multi_match" : {
            "query" : "许",
            "fields": ["title", "sex"]
        }
    }
}

 

还能够额外指定返回值

size指定返回的数量

from指定返回的id起始值

_source指定返回的字段

highlight指定语法高亮

{
    "query": {
        "multi_match" : {
            "query" : "中国",
            "fields": ["nationality", "sex"]
        }
    },
    "size": 2,
    "from": 0,
    "_source": [ "title", "sex", "nationality" ],
    "highlight": {
        "fields" : {
            "title" : {}
        }
    }
}

<4>Boosting

用于提高字段的权重，能够将max_score的分数乘以一个系数

{
    "query": {
        "multi_match" : {
            "query" : "中国",
            "fields": ["nationality^3", "sex"]
        }
    },
    "size": 2,
    "from": 0,
    "_source": [ "title", "sex", "nationality" ],
    "highlight": {
        "fields" : {
            "title" : {}
        }
    }
}

 

<5>组合查询，能够实现一些比较复杂的查询

AND -> must

NOT -> must not

OR -> should

{
    "query": {
        "bool": {
            "must": {
                "bool" : { 
                    "should": [
                      { "match": { "title": "鲍" }},
                      { "match": { "title": "许" }} ],
                    "must": { "match": {"nationality": "中国" }}
                }
            },
            "must_not": { "match": {"sex": "女" }}
        }
    }
}

 <6>模糊（Fuzzy）查询（POST）

{
    "query": {
        "multi_match" : {
            "query" : "厂长",
            "fields": ["title", "sex","occupation"],
            "fuzziness": "AUTO"
        }
    },
    "_source": ["title", "sex", "occupation"],
    "size": 1
}

 经过模糊匹配将 厂长 和 局长 匹配上

AUTO的时候，当query的长度大于5的时候，模糊值指定为2

<7>通配符（Wildcard）查询（POST）

？ 匹配任何字符

* 匹配零个或多个字

{
    "query": {
        "wildcard" : {
            "title" : "*宝"
        }
    },
    "_source": ["title", "sex", "occupation"],
    "size": 1
}

 <8>正则（Regexp）查询（POST）

{
    "query": {
        "regexp" : {
            "authors" : "t[a-z]*y"
        }
    },
    "_source": ["title", "sex", "occupation"],
    "size": 3
}

<9>短语匹配（Match Phrase）查询（POST）

短语匹配查询 要求在请求字符串中的全部查询项必须都在文档中存在，文中顺序也得和请求字符串一致，且彼此相连。

默认状况下，查询项之间必须紧密相连，但能够设置 slop 值来指定查询项之间能够分隔多远的距离，结果仍将被看成一次成功的匹配。

{
    "query": {
        "multi_match" : {
            "query" : "许长江",
            "fields": ["title", "sex","occupation"],
            "type": "phrase"
        }
    },
    "_source": ["title", "sex", "occupation"],
    "size": 3
}

 注意使用slop的时候距离是累加的，滦农局 和 滦县农业局 差了2个距离

{
    "query": {
        "multi_match" : {
            "query" : "滦农局",
            "fields": ["title", "sex","occupation"],
            "type": "phrase",
            "slop":2
        }
    },
    "_source": ["title", "sex", "occupation"],
    "size": 3
}

<10>短语前缀（Match Phrase Prefix）查询（POST）