最近es环境由5.6.4升级到7.3.2，代码里面有很多需要用高版本的api来重写
个人写了一些迁移的总结，如有错误，望请斧正
首先是client，由于es后面将废弃TransportClient，所以代码中都换成RestHighLevelClient
（感觉es 6.0.0是一个版本分界，6.0.0以前是一套，之后是另一套）
建立RestHighLevelClient，因为是http方式，所以是9200端口。以前是tcp方式的client，所以用9300端口
RestHighLevelClient restHighLevelClient = new RestHighLevelClient(RestClient.builder(new HttpHost(esClusterAddress, 9200, "http")));用RestHighLevelClient获取集群所有index
GetAliasesRequest request = new GetAliasesRequest();
GetAliasesResponse getAliasesResponse = restHighLevelClient.indices().getAlias(request,RequestOptions.DEFAULT);
Map<String, Set<AliasMetaData>> map = getAliasesResponse.getAliases();
Set<String> indices = map.keySet();删除index中数据
DeleteByQueryRequest request = new DeleteByQueryRequest(indexName);
BulkByScrollResponse response = restHighLevelClient.deleteByQuery(request, RequestOptions.DEFAULT);删除index
DeleteIndexRequest request = new DeleteIndexRequest("indexName");
AcknowledgedResponse response = restHighLevelClient.indices().delete(request, RequestOptions.DEFAULT);7.0之后看官网说是取消了type
https://www.elastic.co/guide/en/elasticsearch/reference/7.3/mapping.html#field-datatypes
In a cluster composed of both 6.8 and 7.0 nodes, the parameter include_type_name should be specified in index APIs like index creation.
7.0中应该是要指定include_type_name=false
在创建index的时候，指定字段include_in_all:false报错
es文档查了半天，发现从6.0开始，去掉了mapping meta data里面的_all。
Deprecated in 6.0.0.
_all may no longer be enabled for indices created in 6.0+, use a custom field and the mapping copy_to parameterhttps://www.elastic.co/guide/en/elasticsearch/reference/6.8/mapping-all-field.html
找了一篇不错的介绍https://www.cnblogs.com/wangzhuxing/p/9527151.html#_label1_2
es head插件以前用的是0.1.2版本，不支持7.3的查询，查询数据一直卡住。于是想安装新版本的es head插件
https://www.cnblogs.com/bu-dong/p/11578027.html
升级到1.0.8之后可以查询了