elasticsearch-dsl查询

接续上篇，本篇使用python的elasticsearch-dsl库操作elasticsearch进行查询。

7.查询

Elasticsearch是功能非常强大的搜索引擎，使用它的目的就是为了快速的查询到需要的数据。

查询分类：

基本查询：使用es内置查询条件进行查询
组合查询：把多个查询组合在一起进行复合查询
过滤：查询同时，通过filter条件在不影响打分的情况下筛选数据

7.1、基本查询

查询前先创建一张表

 1 PUT chaxun
 2 {
 3   "mappings": {
 4     "job":{
 5       "properties": {
 6         "title":{
 7           "store": true,
 8           "type": "text",
 9           "analyzer": "ik_max_word"
10         },
11         "company_name":{
12           "store": true,
13           "type": "keyword"
14         },
15         "desc":{
16           "type": "text"
17         },
18         "comments":{
19           "type":"integer"
20         },
21         "add_time":{
22           "type":"date",
23           "format": "yyyy-MM-dd"
24         }
25       }
26     }
27   }
28 }

表截图：

match查询

1 GET chaxun/job/_search
2 {
3   "query": {
4     "match": {
5       "title": "python"
6     }
7   }
8 }

1 s = Search(index='chaxun').query('match', title='python')
2 response = s.execute()

term查询

term查询不会对查询条件进行解析（分词）

1 GET chaxun/job/_search
2 {
3   "query": {
4     "term":{
5       "title":"python爬虫"
6     }
7   }
8 }

1 s = Search(index='chaxun').query('term', title='python爬虫')
2 response = s.execute()

terms查询

1 GET chaxun/job/_search
2 {
3   "query": {
4     "terms":{
5       "title":["工程师", "django", "系统"]
6     }
7   }
8 }

1 s = Search(index='chaxun').query('terms', title=['django', u'工程师', u'系统'])
2 response = s.execute()

控制查询的返回数量

 1 GET chaxun/job/_search
 2 {
 3   "query": {
 4     "term":{
 5       "title":"python"
 6     }
 7   },
 8   "from":1,
 9   "size":2
10 }

1 s = Search(index='chaxun').query('terms', title=['django', u'工程师', u'系统'])[0:2]
2 response = s.execute()

match_all 查询所有

1 GET chaxun/job/_search
2 {
3   "query": {
4     "match_all": {}
5   }
6 }

1 s = Search(index='chaxun').query('match_all')
2 response = s.execute()

match_phrase短语查询

 1 GET chaxun/job/_search
 2 {
 3   "query": {
 4     "match_phrase": {
 5       "title": {
 6         "query": "python系统",
 7         "slop": 3
 8       }
 9     }
10   }
11 }

1 s = Search(index='chaxun').query('match_phrase', title={"query": u"elasticsearch引擎", "slop": 3})
2 response = s.execute()

注释：将查询条件“python系统”分词成[“python”, “系统”]，结果需同时满足列表中分词短语，“slop”指定分词词距，匹配结果需不超过slop，比如“python打造推荐引擎系统”，如果slop小于6则无法匹配。

multi_match查询

1 GET chaxun/job/_search
2 {
3   "query": {
4     "multi_match": {
5       "query": "python",
6       "fields": ["title^3", "desc"]
7     }
8   }
9 }

1 q = Q('multi_match', query="python", fields=["title", "desc"])
2 s = Search(index='chaxun').query(q)
3 response = s.execute()

注释：指定查询多个字段，”^3”指定”title”权重是”desc”的3倍。

指定返回字段

1 GET chaxun/job/_search
2 {
3   "stored_fields": ["title", "company_name"],
4   "query": {
5     "match": {
6       "title": "python"
7     }
8   }
9 }

1 s = Search(index='chaxun').query('match', title='python').source(['title', 'company_name'])
2 response = s.execute()

通过sort对结果排序

 1 GET chaxun/job/_search
 2 {
 3   "query": {
 4     "match_all": {}
 5   },
 6   "sort": [
 7     {
 8       "comments": {
 9         "order": "desc"
10       }
11     }
12   ]
13 }

1 s = Search(index='chaxun').query('match_all').sort({"comments": {"order": "desc"}})
2 response = s.execute()

range查询范围

 1 GET chaxun/job/_search
 2 {
 3   "query": {
 4     "range": {
 5       "comments": {
 6         "gte": 10,
 7         "lte": 50,
 8         "boost": 2.0   --权重
 9       }
10     }
11   }
12 }

1 s = Search(index='chaxun').query('range', comments={"gte": 10, "lte": 50, "boost": 2.0})
2 response = s.execute()

wildcard查询

 1 GET chaxun/job/_search
 2 {
 3   "query": {
 4     "wildcard": {
 5       "title": {
 6         "value": "pyth*n",
 7         "boost": 2
 8       }
 9     }
10   }
11 }

1 s = Search(index='chaxun').query('wildcard', title={"value": "pyth*n", "boost": 2})
2 response = s.execute()

7.2、组合查询

- 新建一张查询表

- bool查询

格式如下

1 bool:{
2     "filter":[],
3     "must":[],
4     "should":[],
5     "must_not":[]
6 }

最简单的filter查询

1 select * from testdb where salary=20

 1 GET bool/testdb/_search
 2 {
 3   "query": {
 4     "bool": {
 5       "must": {
 6         "match_all":{}
 7       },
 8      "filter": {
 9         "term":{
10           "salary":20
11         }
12       }
13     }
14   }
15 }

1 s = Search(index='bool').query('bool', filter=[Q('term', salary=20)])
2 response = s.execute()

查看分析器解析（分词）的结果
```
1 GET _analyze
2 {
3   "analyzer": "ik_max_word",
4   "text": "成都电子科技大学"
5 }
```
注释：”ik_max_word”，精细分词；”ik_smart”，粗略分词

bool组合过滤查询

1 select * from testdb where (salary=20 or title=python) and (salary !=30)

 1 GET bool/testdb/_search
 2 {
 3   "query": {
 4     "bool": {
 5       "should": [
 6         {"term":{"salary":20}},
 7         {"term":{"title":"python"}}
 8       ],
 9       "must_not": [
10         {"term":{"salary":30}}
11       ]
12     }
13   }
14 }

1 q = Q('bool', should=[Q('term', salary=20), Q('term', title='python')],must_not=[Q('term', salary=30)])
2 response = s.execute()

嵌套查询

1 select * from testdb where title=python or (title=django and salary=30)

 1 GET bool/testdb/_search
 2 {
 3   "query": {
 4     "bool":{
 5       "should":[
 6         {"term":{"title":"python"}},
 7         {"bool":{
 8           "must":[{"term":{"title":"django"}},
 9                   {"term":{"salary":30}}]
10         }}
11       ]
12     }
13   }
14 }

1 q = Q('bool', should=[Q('term', title='python'), Q('bool', must=[Q('term', title='django'), Q('term', salary=30)])])
2 s = Search(index='bool').query(q)
3 response = s.execute()

过滤空和非空

建立测试数据

 1 POST null/testdb2/_bulk
 2 {"index":{"_id":1}}
 3 {"tags":["search"]}
 4 {"index":{"_id":2}}
 5 {"tags":["search", "python"]}
 6 {"index":{"_id":3}}
 7 {"other_field":["some data"]}
 8 {"index":{"_id":4}}
 9 {"tags":null}
10 {"index":{"_id":5}}
11 {"tags":["search", null]}

处理null空值的方法

1 select tags from testdb2 where tags is not NULL

 1 GET null/testdb2/_search
 2 {
 3   "query": {
 4     "bool":{
 5       "filter": {
 6         "exists": {
 7           "field": "tags"
 8         }
 9       }
10     }
11   }
12 }

7.3、聚合查询

未完待续...

elasticsearch-dsl查询

7.查询

7.1、基本查询

7.2、组合查询

7.3、聚合查询

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