如果你像我开始一样好奇ElasticSearch究竟能干什么？那么文章可能适合你看看。本文对ElasticSearch做一个简介及快速上手，主要例子来源于官网。
本文只需要你安装有docker、可发送curl请求即可操作。
二话不说，先在本地通过docker搭建一个可访问的ElasticSearch服务（以下简称ES）
docker安装ES
docker network create elastic
docker pull docker.elastic.co/elasticsearch/elasticsearch:7.17.3
docker run --name es01-test --net elastic -p 127.0.0.1:9200:9200 -p 127.0.0.1:9300:9300 -e "discovery.type=single-node" docker.elastic.co/elasticsearch/elasticsearch:7.17.3
如果你希望一个可视化操作，可以通过Kibana，本文不做详细介绍，一切从简。
员工文档业务需求：
1.支持包含多值标签、数值、以及全文本的数据
2.检索任一员工的完整信息
3.允许结构化搜索，比如查询30岁以上的员工
4.允许简单的全文搜索以及较复杂的短语搜索
5.支持在匹配文档内容中高亮显示搜索片段
6.支持基于数据创建和管理分析仪表盘（本文不做支持）
介绍
对于员工目录，我们将做如下操作：
1.每个员工索引一个文档，文档包含该员工的所有信息。
2.每个文档都将是 employee 类型 。
3.该类型位于 索引 megacorp 内。
剩下的操作只需要通过curl来请求ES，在终端执行curl即可开始访问。
1.添加单个员工
curl -X PUT "localhost:9200/megacorp/employee/1?pretty" -H 'Content-Type: application/json' -d'
{
"first_name" : "John",
"last_name" : "Smith",
"age" : 25,
"about" : "I love to go rock climbing",
"interests": [ "sports", "music" ]
}
'
2.添加多个员工
curl -X PUT "localhost:9200/megacorp/employee/2?pretty" -H 'Content-Type: application/json' -d'
{
"first_name" : "Jane",
"last_name" : "Smith",
"age" : 32,
"about" : "I like to collect rock albums",
"interests": [ "music" ]
}
'
curl -X PUT "localhost:9200/megacorp/employee/3?pretty" -H 'Content-Type: application/json' -d'
{
"first_name" : "Douglas",
"last_name" : "Fir",
"age" : 35,
"about": "I like to build cabinets",
"interests": [ "forestry" ]
}
'
// 请求
curl -X GET "localhost:9200/megacorp/employee/1?pretty"
// 返回
{
"_index" : "megacorp",
"_type" : "employee",
"_id" : "1",
"_version" : 1,
"_seq_no" : 0,
"_primary_term" : 1,
"found" : true,
"_source" : {
"first_name" : "John",
"last_name" : "Smith",
"age" : 25,
"about" : "I love to go rock climbing",
"interests" : [
"sports",
"music"
]
}
}
3.查询全部员工
// 请求
curl -X GET "localhost:9200/megacorp/employee/_search?pretty"
// 返回
{
"took" : 324,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 3,
"relation" : "eq"
},
"max_score" : 1.0,
"hits" : [
{
"_index" : "megacorp",
"_type" : "employee",
"_id" : "1",
"_score" : 1.0,
"_source" : {
"first_name" : "John",
"last_name" : "Smith",
"age" : 25,
"about" : "I love to go rock climbing",
"interests" : [
"sports",
"music"
]
}
},
{
"_index" : "megacorp",
"_type" : "employee",
"_id" : "2",
"_score" : 1.0,
"_source" : {
"first_name" : "Jane",
"last_name" : "Smith",
"age" : 32,
"about" : "I like to collect rock albums",
"interests" : [
"music"
]
}
},
{
"_index" : "megacorp",
"_type" : "employee",
"_id" : "3",
"_score" : 1.0,
"_source" : {
"first_name" : "Douglas",
"last_name" : "Fir",
"age" : 35,
"about" : "I like to build cabinets",
"interests" : [
"forestry"
]
}
}
]
}
}
4.带条件查询
// 请求
curl -X GET "localhost:9200/megacorp/employee/_search?q=last_name:Smith&pretty"
// 返回
{
"took" : 958,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 2,
"relation" : "eq"
},
"max_score" : 0.4700036,
"hits" : [
{
"_index" : "megacorp",
"_type" : "employee",
"_id" : "1",
"_score" : 0.4700036,
"_source" : {
"first_name" : "John",
"last_name" : "Smith",
"age" : 25,
"about" : "I love to go rock climbing",
"interests" : [
"sports",
"music"
]
}
},
{
"_index" : "megacorp",
"_type" : "employee",
"_id" : "2",
"_score" : 0.4700036,
"_source" : {
"first_name" : "Jane",
"last_name" : "Smith",
"age" : 32,
"about" : "I like to collect rock albums",
"interests" : [
"music"
]
}
}
]
}
}
5.使用查询表达式搜索
// 请求
curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
"query" : {
"match" : {
"last_name" : "Smith"
}
}
}
'
// 返回 (同例4)
6.复杂查询
curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
"query" : {
"bool": {
"must": {
"match" : {
"last_name" : "smith"
}
},
"filter": {
"range" : {
"age" : { "gt" : 30 }
}
}
}
}
}
'
7.关联查询
curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
"query" : {
"match" : {
"about" : "rock climbing"
}
}
}
'
8.短语查询
curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
"query" : {
"match_phrase" : {
"about" : "rock climbing"
}
}
}
'
9.1聚合
// 请求
curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
"aggs": {
"all_interests": {
"terms": { "field": "interests.keyword" }
}
}
}
'
// 返回
{
"took" : 454,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 3,
"relation" : "eq"
},
"max_score" : 1.0,
"hits" : [
{
"_index" : "megacorp",
"_type" : "employee",
"_id" : "1",
"_score" : 1.0,
"_source" : {
"first_name" : "John",
"last_name" : "Smith",
"age" : 25,
"about" : "I love to go rock climbing",
"interests" : [
"sports",
"music"
]
}
},
{
"_index" : "megacorp",
"_type" : "employee",
"_id" : "2",
"_score" : 1.0,
"_source" : {
"first_name" : "Jane",
"last_name" : "Smith",
"age" : 32,
"about" : "I like to collect rock albums",
"interests" : [
"music"
]
}
},
{
"_index" : "megacorp",
"_type" : "employee",
"_id" : "3",
"_score" : 1.0,
"_source" : {
"first_name" : "Douglas",
"last_name" : "Fir",
"age" : 35,
"about" : "I like to build cabinets",
"interests" : [
"forestry"
]
}
}
]
},
"aggregations" : {
"all_interests" : {
"doc_count_error_upper_bound" : 0,
"sum_other_doc_count" : 0,
"buckets" : [
{
"key" : "music",
"doc_count" : 2
},
{
"key" : "forestry",
"doc_count" : 1
},
{
"key" : "sports",
"doc_count" : 1
}
]
}
}
}
9.2 聚合+条件
curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
"query": {
"match": {
"last_name": "smith"
}
},
"aggs": {
"all_interests": {
"terms": {
"field": "interests.keyword"
}
}
}
}
'
9.3 聚合+结果
curl -X GET "localhost:9200/megacorp/employee/_search?pretty" -H 'Content-Type: application/json' -d'
{
"aggs" : {
"all_interests" : {
"terms" : { "field" : "interests.keyword" },
"aggs" : {
"avg_age" : {
"avg" : { "field" : "age" }
}
}
}
}
}
'
相信一通操作下来就有点感觉了，和Mysql的insert、select可以对比一下，当然目前为止这还只是ES最简单的套路。
总结
本文通过docker运行es，并给出员工的例子进行了简单介绍。
Q1:再次运行docker run时遇到报错
docker: Error response from daemon: Conflict. The container name "/es01-test" is already in use by container "414ad17fb21a8a0ac7295bda1440a5646a92110f7f9ed94c5dcfd291d8213d64". You have to remove (or rename) that container to be able to reuse that name.
解决：docker rm es01-test删除镜像后重新操作即可。
Reference
ES快速上手：https://www.elastic.co/guide/en/elasticsearch/reference/7.17/getting-started.html#getting-started
ES权威指南：https://www.elastic.co/guide/cn/elasticsearch/guide/current/index.html 章节《你知道的, 为了搜索…》
