前言:
此时小伙伴们对“es查询索引下的数据”可能比较注意,朋友们都需要知道一些“es查询索引下的数据”的相关知识。那么小编在网络上汇集了一些对于“es查询索引下的数据””的相关知识,希望朋友们能喜欢,大家快快来了解一下吧!基本查询
基本语法:
GET /索引库名/_search{ "query":{ "查询类型":{ "查询条件":"查询条件值" } }}
这里的 query 代表一个查询对象,里面可以有不同的查询属性。
查询类型:match_all、match、term、range 等等。
查询条件:查询条件会根据类型的不同,写法也有差异。
查询所有(match_all)
示例:
GET /renda/_search{ "query":{ "match_all": {} }}
query:代表查询对象。
match_all:代表查询所有。
结果:
{ "took": 1, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 3, "max_score": 1, "hits": [ { "_index": "renda", "_type": "goods", "_id": "2", "_score": 1, "_source": { "title": "白米手机", "images": ";, "price": 2699 } }, { "_index": "renda", "_type": "goods", "_id": "gPeQqHUB-UTJAEEuqOm9", "_score": 1, "_source": { "title": "小米手机", "images": ";, "price": 2699 } }, { "_index": "renda", "_type": "goods", "_id": "3", "_score": 1, "_source": { "title": "超大米手机", "images": ";, "price": 3299, "stock": 200, "saleable": true, "subTitle": "大米" } } ] }}
结果解析:
took - 检索所耗费的时间,单位是毫秒。timed_out - 是否超时。_shards - 分片信息。hits - 命中结果,检索结果信息。 total - 搜索到的总条数。 max_score - 所有结果中文档得分的最高分。 hits - 搜索结果的文档对象数组,每个元素是一条搜索到的文档信息。 _index - 索引库。 _type - 文档类型。 _id - 文档 id。 _score - 评分;索引库的一个概念;关联度。 _source - 原始数据。
文档得分:使用 ES 时,对于查询出的文档无疑会有文档相似度之别;而理想的排序是和查询条件相关性越高排序越靠前,而这个排序的依据就是 _score。
匹配查询(match)
加入一条数据用于测试:
PUT /renda/goods/3{ "title": "小米电视4A", "images": ";, "price": 3899.00}
索引库中有 3 部手机,1 台电视。
match 类型查询,会把查询条件进行分词,然后进行查询,多个词条之间是 or 的关系:
GET /renda/_search{ "query": { "match": { "title": "小米电视" } }}
响应结果:
{ "took": 15, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 2, "max_score": 0.5753642, "hits": [ { "_index": "renda", "_type": "goods", "_id": "3", "_score": 0.5753642, "_source": { "title": "小米电视4A", "images": ";, "price": 3899 } }, { "_index": "renda", "_type": "goods", "_id": "gPeQqHUB-UTJAEEuqOm9", "_score": 0.2876821, "_source": { "title": "小米手机", "images": ";, "price": 2699 } } ] }}
在上面的案例中,不仅会查询到电视,而且与小米相关的都会查询到,多个词之间是 or 的关系。
某些情况下,需要更精确查找,即 and 关系。比如在电商平台精确搜索商品时,希望这个关系(查询条件切分词之后的关系)变成 and,可以这样做:
GET /renda/_search{ "query": { "match": { "title": { "query": "小米电视", "operator": "and" } } }}
响应结果:
{ "took": 8, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 1, "max_score": 0.5753642, "hits": [ { "_index": "renda", "_type": "goods", "_id": "3", "_score": 0.5753642, "_source": { "title": "小米电视4A", "images": ";, "price": 3899 } } ] }}
此时,只有同时包含小米和电视的词条才会被搜索到。
词条匹配(term)
term 查询被用于精确值匹配,这些精确值可能是数字、时间、布尔,或者那些未分词的字符串、keyword 类型的字符串。
效果类似于:select * from tableName where colName='value';
GET /renda/_search{ "query":{ "term":{ "price": 2699.00 } }}
响应结果:
{ "took": 6, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 2, "max_score": 1, "hits": [ { "_index": "renda", "_type": "goods", "_id": "2", "_score": 1, "_source": { "title": "白米手机", "images": ";, "price": 2699 } }, { "_index": "renda", "_type": "goods", "_id": "gPeQqHUB-UTJAEEuqOm9", "_score": 1, "_source": { "title": "小米手机", "images": ";, "price": 2699 } } ] }}布尔组合(bool)
bool 把各种其它查询通过 must - 与、 must_not - 非、 should - 或 的方式进行组合。
GET /renda/_search{ "query":{ "bool":{ "must": { "match": { "title": "小米" } }, "must_not": { "match": { "title": "电视" } }, "should": { "match": { "title": "手机" } } } }}
响应结果:
{ "took": 2, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 1, "max_score": 0.5753642, "hits": [ { "_index": "renda", "_type": "goods", "_id": "gPeQqHUB-UTJAEEuqOm9", "_score": 0.5753642, "_source": { "title": "小米手机", "images": ";, "price": 2699 } } ] }}范围查询(range)
range 查询找出那些落在指定区间内的数字或者时间。
GET /renda/_search{ "query": { "range": { "price": { "gte": 3000.0, "lt": 4000.00 } } }}
响应结果:
{ "took": 1, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 1, "max_score": 1, "hits": [ { "_index": "renda", "_type": "goods", "_id": "3", "_score": 1, "_source": { "title": "小米电视4A", "images": ";, "price": 3899 } } ] }}
range 查询允许以下字符:
gt - 大于gte - 大于等于lt - 小于lte - 小于等于模糊查询(fuzzy)
fuzzy 查询是 term 查询的模糊等价,很少直接使用它。
新增一个商品:
POST /renda/goods/5{ "title": "Apple手机", "images": ";, "price": 6899.00}
响应结果:
{ "_index": "renda", "_type": "goods", "_id": "5", "_version": 1, "result": "created", "_shards": { "total": 2, "successful": 1, "failed": 0 }, "_seq_no": 0, "_primary_term": 2}
fuzzy 查询是 term 查询的模糊等价,它允许用户搜索词条与实际词条的拼写出现偏差,但是偏差的编辑距离不得超过 2:
GET /renda/_search{ "query": { "fuzzy": { "title": "applas" } }}
上面的查询,也能查询到 apple 手机:
{ "took": 4, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 1, "max_score": 0.17260925, "hits": [ { "_index": "renda", "_type": "goods", "_id": "5", "_score": 0.17260925, "_source": { "title": "Apple手机", "images": ";, "price": 6899 } } ] }}
结果过滤
默认情况下,Elasticsearch 在搜索的结果中,会把文档中保存在 _source 的所有字段都返回。
如果只想获取其中的部分字段,可以添加 _source 的过滤。
直接指定字段
示例:
GET /renda/_search{ "_source": ["title","price"], "query": { "term": { "price": 2699 } }}
返回的结果:
{ "took": 2, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 2, "max_score": 1, "hits": [ { "_index": "renda", "_type": "goods", "_id": "2", "_score": 1, "_source": { "price": 2699, "title": "白米手机" } }, { "_index": "renda", "_type": "goods", "_id": "gPeQqHUB-UTJAEEuqOm9", "_score": 1, "_source": { "price": 2699, "title": "小米手机" } } ] }}指定 includes 和 excludes
includes:来指定想要显示的字段。
excludes:来指定不想要显示的字段。
二者都是可选的。
示例:
GET /renda/_search{ "_source": { "includes":["title", "price"] }, "query": { "term": { "price": 2699 } }}
与下面的结果将是一样的:
GET /renda/_search{ "_source": { "excludes": ["images"] }, "query": { "term": { "price": 2699 } }}
响应结果:
{ "took": 1, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 2, "max_score": 1, "hits": [ { "_index": "renda", "_type": "goods", "_id": "2", "_score": 1, "_source": { "price": 2699, "title": "白米手机" } }, { "_index": "renda", "_type": "goods", "_id": "gPeQqHUB-UTJAEEuqOm9", "_score": 1, "_source": { "price": 2699, "title": "小米手机" } } ] }}
过滤(Filter)
Elasticsearch 使用的查询语言(DSL)拥有一套查询组件,这些组件可以以无限组合的方式进行搭配。
这套组件可以在以下两种情况下使用:过滤情况 - filtering context 和查询情况 - query context。
如何选择查询与过滤:
通常的规则是,使用查询(query)语句来进行全文搜索或者其它任何需要影响相关性得分的搜索;除此以外的情况都使用过滤(filters)。
条件查询中进行过滤:
所有的查询都会影响到文档的评分及排名。如果需要在查询结果中进行过滤,并且不希望过滤条件影响评分,那么就不要把过滤条件作为查询条件来用,而是使用 filter 方式:
GET /renda/_search{ "query":{ "bool":{ "must":{ "match": { "title": "小米手机" }}, "filter":{ "range":{"price":{"gt":2000.00,"lt":3800.00}} } } }}
无查询条件,直接过滤:
如果一次查询只有过滤,没有查询条件,不希望进行评分,可以使用 constant_score 取代只有 filter 语句的 bool 查询。在性能上是完全相同的,但对于提高查询简洁性和清晰度有很大帮助。
GET /renda/_search{ "query":{ "constant_score": { "filter": { "range": {"price":{"gt":2000.00, "lt":3000.00}} } } }}
排序单字段排序
sort 可以按照不同的字段进行排序,并且通过 order 指定排序的方式。
GET /renda/_search{ "query": { "match": { "title": "小米手机" } }, "sort": [ { "price": { "order": "desc" } } ]}多字段排序
假定想要结合使用 price 和 _score 进行查询,并且匹配的结果首先按照价格排序,然后按照相关性得分排序:
GET /renda/_search{ "query": { "bool": { "must": { "match": { "title": "小米手机" } }, "filter":{ "range": { "price": { "gt":2000, "lt":4000 } } } } }, "sort": [ { "price": { "order": "desc" } }, { "_score": { "order": "desc" } } ]}
分页
Elasticsearch 中数据都存储在分片中,当执行搜索时每个分片独立搜索后,数据再经过整合返回。那么,如何实现分页查询呢?
Elasticsearch 的分页与 MySQL 数据库非常相似,都是指定两个值:
from - 目标数据的偏移值(开始位置),默认 from 为 0。size - 每页大小。
GET /renda/_search{ "query": { "match_all": {} }, "sort": [ { "price": { "order": "asc" } } ], "from": 3, "size": 3}
结果:
{ "took": 1, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 4, "max_score": null, "hits": [ { "_index": "renda", "_type": "goods", "_id": "5", "_score": null, "_source": { "title": "Apple手机", "images": ";, "price": 6899 }, "sort": [ 6899 ] } ] }}
高亮
高亮原理:
服务端搜索数据,得到搜索结果。把搜索结果中,搜索关键字都加上约定好的标签。前端页面提前写好标签的 CSS 样式,即可高亮。
Elasticsearch 中实现高亮的语法比较简单:
GET /renda/_search{ "query": { "match": { "title": "手机" } }, "highlight": { "pre_tags": "<em>", "post_tags": "</em>", "fields": { "title": {} } }}
在使用 match 查询的同时,加上一个 highlight 属性:
pre_tags:前置标签post_tags:后置标签fields:需要高亮的字段 title:这里声明 title 字段需要高亮
结果:
{ "took": 2, "timed_out": false, "_shards": { "total": 5, "successful": 5, "skipped": 0, "failed": 0 }, "hits": { "total": 3, "max_score": 0.2876821, "hits": [ { "_index": "renda", "_type": "goods", "_id": "5", "_score": 0.2876821, "_source": { "title": "Apple手机", "images": ";, "price": 6899 }, "highlight": { "title": [ "Apple<em>手机</em>" ] } }, { "_index": "renda", "_type": "goods", "_id": "2", "_score": 0.2876821, "_source": { "title": "白米手机", "images": ";, "price": 2699 }, "highlight": { "title": [ "白米<em>手机</em>" ] } }, { "_index": "renda", "_type": "goods", "_id": "gPeQqHUB-UTJAEEuqOm9", "_score": 0.2876821, "_source": { "title": "小米手机", "images": ";, "price": 2699 }, "highlight": { "title": [ "小米<em>手机</em>" ] } } ] }}
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标签: #es查询索引下的数据