Download and install: https://www.elastic.co/cn/downloads/

concept

　　ElasticSearch is a distributed, highly scalable, high real-time search and data analysis engine. It is easy to make large amounts of data with a search, analysis and exploration. ElasticSearch full utilization level of stretchability, can become more valuable data in a production environment. The principle of ElasticSearch divided into the following steps, first of all user data will be submitted to the Elastic Search database, and then through word controller to the corresponding word statement, its weight and the results are stored in the data word, when a user searches time data, then the weight will be based on the results of the ranking, scoring, and then returns the results to the user. Based on the underlying Lucene.

　　Elasticsearch is called Logstash data collection and analysis and log analysis engines and visualization platform called Kibana developed together. These three products are designed to be an integrated solution, called "Elastic Stack" (formerly called "ELK stack").

Full-text search, index (schematic) inverted

lucene

lucene. is a jar package, which contains (packaged variety create an inverted index, and search code, including various algorithms, when we use java development, the introduction of lucene jar, then that is developed based on the lucene api can use lucene, we can go to the existing data indexing, lucene will be in the local disk above, to our organization index data structures. Some features in addition, we can also use lucene provided and api come on for the disk the index data for searching.

Elasticsearch

1.自动维护数据的分布到多个节点索引的建立，还有搜索请术分布到多个节点的执行
2.自动维护数据的冗余副本，包证说，一些机器宕机了，不会丢失任何的数据
3.封装了更多的高级功能，以给我们提供更多高级的支持，让我们快速的开发应用，开发更加复杂的应用，复杂的搜索功能，聚合分析的功能，基于地理位置的搜素（距离我当前位置1公里以内的烤内店）

shard和replica

shard：单机器无法存储大量数据，es可以将一个索引中的数据切分为多个shard，分布在多台服务器上存储。有了shard就可以横向扩展，存储更多数据，让搜索和分析等操作分不到多态服务器上去执行，提高吞吐量和性能。，每一个share都是一个Lucene index
replica：任何服务器随时可能故障或宕机，此时shard可能就会丢失，因此可以为每个shard创建多个replica副本。replica可以在shard故障时提供备用服务，保证数据不丢失，多个replica还可以提供检索操作的吞吐量和性能。primary share（建立索引时一次设置，不能修改，默认5个），replica shard（随时修改数重，默认1个，默认每个索引10个shard，5个primary shard，5个replica shard，最小的高可用配置，是2台服务器。

index和type和document

ES中document相当数据库中的一行。

ES中的type相当数据库中的表

ES中的index相当数据库中的数据库

使用

windows启动

启动命令(进入bin目录)

elasticsearch.bat

如果出现

ElasticsearchException[X-Pack is not supported and Machine Learning is not available for [windows-x86]; you can use the other X-Pack features (unsupported) by setting xpack.ml.enabled: false in elasticsearch.yml错误

解决：在elasticsearch.yml配置文件最后添加，重新启动

xpack.ml.enabled: false

访问浏览器

http://127.0.0.1:9200/

出现，表示启动陈宫

{
  "name" : "xxxx-PC",    //表示node(节点名称)：在哪一台服务器上启动
  "cluster_name" : "elasticsearch", //集群名称，如果需要修改，在conf/elasticsearch.yml中修改
  "cluster_uuid" : "SSOU_2kJSW6xsHZFwfLrhg",
  "version" : {
    "number" : "7.2.0",
    "build_flavor" : "default",
    "build_type" : "zip",
    "build_hash" : "508c38a",
    "build_date" : "2019-06-20T15:54:18.811730Z",
    "build_snapshot" : false,
    "lucene_version" : "8.0.0",
    "minimum_wire_compatibility_version" : "6.8.0",
    "minimum_index_compatibility_version" : "6.0.0-beta1"
  },
  "tagline" : "You Know, for Search"
}

使用kibana

Kibana是一个开源的分析和可视化平台，设计用于和Elasticsearch一起工作。

启动（bin目录下）

kabana.bat

打开浏览器

http://localhost:5601

使用开发工具(dev tools)操作下面的命令

集群操作

GET /_cluster/health               
GET _cat/health?v          查看集群健康状况，status="green":表示每个索引的primary shard和replica shard都是active状态的
　　　　　　　　　　　　　　　　　　　　　　　　　　　　 ="yellow": 表示每个索引的primary shard是active，但是部分replica shard都是不是active状态的
　　　　　　　　　　　　　　　　　　　　　　　　　　　　 ="red":表示不是所有索引的primary shard是active，部分索引有数据丢失。
GET _cat/indices?v         快速查看集群中索引的情况

PUT /index_test?pretty     新建索引 index_test:测试的索引名
DELETE /index_test         删除index_test索引

数据的crud

put /index/type/id
{
 "json数据"
}
示例：
PUT /test/test1/1         es会自动创建index和type
{
"name":"zy"
}

Elasticsearch ---- basis