-1.https://www.elastic.co/guide/en/elasticsearch/reference/7.2/removal-of-types.html  include_type_name

0.概念

The force merge API allows to force merging of one or more indices through an API.

Force merge should only be called against read-only indices. Running force merge against a read-write index can cause very large segments to be produced

Lucene每次会选取一些小的segments 进而merge到一个大的segment

 

1.命令

curl -X POST "192.168.1.111:9200/mytest/_forcemerge?pretty"
参考：https://www.elastic.co/guide/en/elasticsearch/reference/6.8/indices-forcemerge.html


2.原理

2.4ES写入数据的过程：

客户端选择一个node发送请求过去，这个node就是coordinating node (协调节点)
coordinating node，对document进行路由，将请求转发给对应的node
实际上的node上的primary shard处理请求，然后将数据同步到replica node
coordinating node，如果发现primary node和所有的replica node都搞定之后，就会返回请求到客户端
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用一个例子来演示会更加清晰