ES 查询
1、构造运行环境
打开kibana进入Dev tools,创建索引,并插入测试数据,代码如下:
PUT /logs/_doc/1
{
"Name":"燕麦",
"Desc":"燕麦商品描述",
"Price":111,
"Tags":["Breakfast","Carbon","Cheap"]
}
PUT /logs/_doc/2
{
"Name":"牛奶",
"Desc":"牛奶商品描述",
"Price":222,
"Tags":["Breakfast","Nutrition","Expensive"]
}
PUT /logs/_doc/3
{
"Name":"面包",
"Desc":"牛奶商品描述",
"Price":333,
"Tags":["Breakfast","Barley","Cheap","Carbon"]
}
PUT /logs/_doc/4
{
"Name":"玉米",
"Desc":"玉米商品描述",
"Price":444,
"Tags":["Breakfast","Vegetables","Cheap","Carbon"]
}
PUT /logs/_doc/5
{
"Name":"葡萄",
"Desc":"葡萄商品描述",
"Price":555,
"Tags":["Breakfast","Fruits","Expensive","Carbon"]
}执行以上代码,并执行搜索,查看数据是否插入,简单搜索代码如下:
GET /logs/_search或者
GET /logs/_search
{
"query": {
"match_all": {}
}
}注：这里相当于select * from 表名 where 1=1,match_all相当于匹配所有.
查询结果集如下:
{
"took": 2,//当前请求花费的时间
"timed_out": false,//当前请求是否超时
//当前请求的分片情况
"_shards": {
"total": 1,
"successful": 1,
"skipped": 0,
"failed": 0
},
"hits": {
"total": {
"value": 5,//当前请求查询到5条结果
"relation": "eq" //当前查询的关系是等于
},
"max_score": 1, //当前查询的评分,最大是1.0
"hits": [
{
"_index": "logs",
"_id": "1",
"_score": 1,
"_source": {
"Name": "燕麦",
"Desc": "燕麦商品描述",
"Price": 111,
"Tags": [
"Breakfast",
"Carbon",
"Cheap"
]
}
},
{
"_index": "logs",
"_id": "2",
"_score": 1,
"_source": {
"Name": "牛奶",
"Desc": "牛奶商品描述",
"Price": 222,
"Tags": [
"Breakfast",
"Nutrition",
"Expensive"
]
}
},
{
"_index": "logs",
"_id": "3",
"_score": 1,
"_source": {
"Name": "面包",
"Desc": "牛奶商品描述",
"Price": 333,
"Tags": [
"Breakfast",
"Barley",
"Cheap",
"Carbon"
]
}
},
{
"_index": "logs",
"_id": "4",
"_score": 1,
"_source": {
"Name": "玉米",
"Desc": "玉米商品描述",
"Price": 444,
"Tags": [
"Breakfast",
"Vegetables",
"Cheap",
"Carbon"
]
}
},
"_index": "logs",
"_id": "5",
"_score": 1,
"_source": {
"Name": "葡萄",
"Desc": "葡萄商品描述",
"Price": 555,
"Tags": [
"Breakfast",
"Fruits",
"Expensive",
"Carbon"
]
}
}
]
}
}这里插入成功了.
2、相关度评分
1中的demo查询结果集中有一个max_score字段就是相关度评分,当使用查询接口时没有指定排序字段,那么ES就会按照每条记录的评分进行排序.相关度评分中涉及到两种算法,会在后续的文章中进行介绍.
3、元数据
1中的demo查询结果集有一个source字段就是元数据,其大致结构如下
"_source": {
"Name": "燕麦",
"Desc": "燕麦商品描述",
"Price": 111,
"Tags": [
"Breakfast",
"Carbon",
"Cheap"
]
}结果类似与关系型数据库中的表字段和相关的值.
3.1、禁用元数据(source)
3.1.1 优缺点
优点:节省存储开销
缺点:不支持update、update_by_query、reindex_api、不支持高亮、不支持reindex,更改mapping分析器以及版本升级、通过索引时查看原文档进行聚合查询会失效、导致自动修复索引的功能实现.
注：如果单纯为了介绍存储开销,可以使用压缩索引,比禁用source更好.
3.1.2 通过创建索引时指定mapping配置来控制source
缺点：通过创建索引时指定mapping配置,来强制限制souce的字段查询的方式或者在mapping中禁用source,设置之后将无法修改.
(1)、完全禁用source
PUT /logs
{
"mappings": {
"_source": {
"enabled": false
}
}
}(2)、禁用source中的部分字段
PUT /logs
{
"mappings": {
"_source": {
"includes": [
"Name",
"Tags"
],
"excludes": [
"Price",
"Desc"
]
}
}
}通过指定includes和excludes来展示和禁用source中的字段
注：不推荐使用mapping的方式来控制source！！！！！！！
3.1.3 通过在查询条件来控制source
(1)、查询时禁用mapping
GET /logs/_search
{
"_source":false,
"query": {
"match_all": {}
}
}这时结果集中不会包含mapping等相关信息,只包含index、id、score等相关信息.
(2)、常规搜索
GET /logs/_search
{
"_source": ["Name","Tags"],
"query": {
"match_all": {}
}
}通过在api中指定_source来控制查询结果返回的字段,类似与关系型数据库中的 select Name,Tags from logs;
(3)、通配符查找
删除1demo中的索引,新建以下索引
PUT /logs/_doc/1
{
"Name":"燕麦",
"Desc":"燕麦商品描述",
"Price":111,
"Items":{
"Name":"子名称",
"Price":222
},
"Tags":["Breakfast","Carbon","Cheap"]
}logs索引中包含一个Items的对象属性,如果此时搜索只希望查Items的相关信息,可以执行以下操作
GET /logs/_search
{
"_source":["Items.*"],
"query": {
"match_all": {}
}
}返回的结果如下:
"hits": [
{
"_index": "logs",
"_id": "1",
"_score": 1,
"_source": {
"Items": {
"Price": 222,
"Name": "子名称"
}
}
}
](4)、includes查看和exincludes查找
GET /logs/_search
{
"_source":{
"includes": ["Items.*","Price","Desc"],
"excludes": ["Name"]
},
"query": {
"match_all": {}
}
}这里可以指定查询包含哪些字段和不包含哪些字段
4、QueryString 查询
4.1 查询所有
GET /logs/_search4.2 分页搜索
GET /logs/_search?from=0&size=3&sort=Price:desc查询从第from条开始,一共查size条数据,排序条件时Price按desc排序.
4.3 精准匹配
GET /logs/_search?q=Name:牛奶这里查询的就是log中Name索引集合中值为牛奶的document.
注:ES默认会为所有的字段创建倒排索引,如果通过q=字段:字段值的形式进行搜索,ES会去指定字段的索引集合查找相关的值并返回.
4.4 all搜索
GET /logs/_search?q=111重点注意:ES默认会为所有的字段创建倒排索引,所以如4.3中一样,查询条件没有以q=字段:字段值的形式进行搜索,ES扫描所有建立了倒排索引的字段.所以这里的结果集如下:
"hits": [
{
"_index": "logs",
"_id": "2",
"_score": 1.3167865,
"_source": {
"Name": "牛奶",
"Desc": "牛奶商品描述111",
"Price": 222,
"Tags": [
"Breakfast",
"Nutrition",
"Expensive"
]
}
},
{
"_index": "logs",
"_id": "1",
"_score": 1,
"_source": {
"Name": "燕麦",
"Desc": "燕麦商品描述",
"Price": 111,
"Tags": [
"Breakfast",
"Carbon",
"Cheap"
]
}
}
]Price和Desc中包含111的记录都被检索出来了.
注：这里需要注意精准匹配的问题.demo中Desc字段会被分词,在进行匹配,但是Price并不会.！！！