elasticsearch Elasticsearch：如何实现区分大小写的术语查询？

我尝试通过名为unit的字段来查询项目，该字段区分大小写（如kWh），但我的术语查询仅在查询kWh（小写W）时匹配。我在文档中看到的是，这个术语应该是区分大小写的正确术语，所以我不确定我做错了什么

## Create an item
curl -X POST "localhost:9200/my_index/my_type/my_id" -H 'Content-Type: application/json' -d'{"point_name" : "my_point_name", "unit" : "kWh"}'
=> {"_index":"my_index","_type":"my_type","_id":"my_id","_version":1,"result":"created","_shards":{"total":2,"successful":1,"failed":0},"created":true}

## Try to query it by unit with exact match (kWh)
curl -X GET "localhost:9200/my_index/my_type/_search" -H 'Content-Type: application/json' -d'{"query" : { "bool" : {"must" : [{ "term" : {"unit" : "kWh"}}]}}}'
=> {"took":36,"timed_out":false,"_shards":{"total":5,"successful":5,"skipped":0,"failed":0},"hits":{"total":0,"max_score":null,"hits":[]}}

## Query with lower case unit kwh
curl -X GET "localhost:9200/my_index/my_type/_search" -H 'Content-Type: application/json' -d'{"query" : { "bool" : {"must" : [{ "term" : {"unit" : "kwh"}}]}}}'
=> {"took":12,"timed_out":false,"_shards":{"total":5,"successful":5,"skipped":0,"failed":0},"hits":{"total":1,"max_score":0.2876821,"hits":[{"_index":"my_index","_type":"my_type","_id":"my_id","_score":0.2876821,"_source":{"point_name" : "my_point_name", "unit" : "kWh"}}]}}

我不想在这里使用match，因为我也通过其他字段创建这些查询，并且我希望确保精确的匹配行为。有人能告诉我这个查询如何正确，为什么这个术语查询不起作用吗

我正在使用此dockerimage作为我的服务器：

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docker.elastic.co/elasticsearch/elasticsearch:6.2.4

您应该检查字段

单元的类型。很可能是
文本
，它是
分析的
，将存储小写的术语。您需要的是
关键字
类型。如果您使用的是“默认”映射，那么很可能存在一个
unit.keyword
字段，该字段将与
术语
查询区分大小写。另见。啊，谢谢你。关键字解决了我的问题。如果你喜欢写一个答案，我会接受它的伟大！没关系，我想这个问题已经被问了很多次了：）