Elasticsearch indexing the same data

Question

I have created a river in the following way:

curl -XPUT 'localhost:9200/test1/hello1/_meta' -d 
'{
    "type" : "jdbc",
    "jdbc" : {
        "url" : "jdbc:mysql://localhost:3306/tdb",
        "user" : "root",
        "password" : "",
        "sql" : "select * from test "

    }


}'

I have made get request:

curl -XGET 'localhost:9200/jdbc/_search?pretty&q=*'

It indexes the data,but next time when I change the query in a different river: curl -XGET 'localhost:9200/jdbc/_search?pretty&q=*'

It displays the same indexed data as for the previous river.