# 一个 field 索引两次解决字符串排序
如果对一个 string field 进行排序，结果往往不准确，因为分词后是多个单词，再排序就不是我们想要的结果了
通常解决方案是，将一个 string field 建立两次索引，一个分词，用来进行搜索；一个不分词，用来进行排序
先来建立 mapping，将 title 索引两次，注意语法
PUT /website
{
"mappings": {
"article": {
"properties": {
"title": {
"type": "text",
"fields": {
"raw": {
"type": "string",
"index": "not_analyzed"
}
},
"fielddata": true
},
"content": {
"type": "text"
},
"post_date": {
"type": "date"
},
"author_id": {
"type": "long"
}
}
}
}
}
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TIP
对一个 text、string 字段进行排序，需要正排索引，使用 fielddata 属性来开启
记得查询看下 mapping 数据
GET /website/_mapping
-------------------------- 响应
{
"website": {
"mappings": {
"article": {
"properties": {
"author_id": {
"type": "long"
},
"content": {
"type": "text"
},
"post_date": {
"type": "date"
},
"title": {
"type": "text",
"fields": {
"raw": {
"type": "keyword"
}
},
"fielddata": true
}
}
}
}
}
}
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插入两条数据,注意第 2条 数据的 title 的首字母，g 排序的话，就会在后面
PUT /website/article/1
{
"title": "first article",
"content": "this is my second article",
"post_date": "2017-01-01",
"author_id": 110
}
PUT /website/article/2
{
"title": "girst article",
"content": "this is my second article",
"post_date": "2017-01-01",
"author_id": 110
}
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直接查询, 后插入的在前面
GET /website/article/_search
{
"took": 5,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 2,
"max_score": 1,
"hits": [
{
"_index": "website",
"_type": "article",
"_id": "2",
"_score": 1,
"_source": {
"title": "girst article",
"content": "this is my second article",
"post_date": "2017-01-01",
"author_id": 110
}
},
{
"_index": "website",
"_type": "article",
"_id": "1",
"_score": 1,
"_source": {
"title": "first article",
"content": "this is my second article",
"post_date": "2017-01-01",
"author_id": 110
}
}
]
}
}
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使用 title 升序排列，可以看到 sort 中使用的是分词后的一个单词来排序
GET /website/article/_search
{
"query": {},
"sort": [
{
"title": {
"order": "asc"
}
}
]
}
----------------- 响应
{
"took": 3,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 2,
"max_score": null,
"hits": [
{
"_index": "website",
"_type": "article",
"_id": "2",
"_score": null,
"_source": {
"title": "girst article",
"content": "this is my second article",
"post_date": "2017-01-01",
"author_id": 110
},
"sort": [
"article"
]
},
{
"_index": "website",
"_type": "article",
"_id": "1",
"_score": null,
"_source": {
"title": "first article",
"content": "this is my second article",
"post_date": "2017-01-01",
"author_id": 110
},
"sort": [
"article"
]
}
]
}
}
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使用 title.raw 来排序
GET /website/article/_search
{
"query": {},
"sort": [
{
"title.raw": {
"order": "asc"
}
}
]
}
--------------------- 响应
{
"took": 1,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 2,
"max_score": null,
"hits": [
{
"_index": "website",
"_type": "article",
"_id": "1",
"_score": null,
"_source": {
"title": "first article",
"content": "this is my second article",
"post_date": "2017-01-01",
"author_id": 110
},
"sort": [
"first article"
]
},
{
"_index": "website",
"_type": "article",
"_id": "2",
"_score": null,
"_source": {
"title": "girst article",
"content": "this is my second article",
"post_date": "2017-01-01",
"author_id": 110
},
"sort": [
"girst article"
]
}
]
}
}
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