elasticsearch中文文档 “映射和分析” 一章的疑问

Question

文档连接 这里

上面的例子完全实现不了啊

我试着如下操作:

POST /gb/tweet/_bulk
{ "index": { "_id": 1 }}
{ "name" : "高性能MySQL", "user_id" : "15", "tweet" : "page's number is gt than 700" , "create_at":"2015-09-25"}
{ "index": { "_id": 2 }}
{ "name" : "Elasticsearch 权威指南", "user_id" : "5", "tweet" : "this is a very nice book" , "create_at":"2018-02-11"}
{ "index": { "_id": 3 }}
{ "name" : "Solr 实战", "user_id" : "1098", "tweet" : "my next book" , "create_at":"2017-06-06"}
{ "index": { "_id": 4 }}
{ "name" : "Kafka 内核分析", "user_id" : "79", "tweet" : "kafka need to compare with rabbitmq" , "create_at":"2016-08-06"}

GET /gb/tweet/_search
GET /gb/_mapping/tweet
GET /gb/tweet/_search?q=2018        这个完全没有结果啊
GET /gb/tweet/_search?q=2015-09-25
GET /gb/tweet/_search?q=create_at:2015
GET /gb/tweet/_search?q=create_at:2015-09-25