logstash-input-mongodb 这两条DEBUG一直循环打印出来；数据并没有导入es中

D, [2018-03-02T10:56:45.074114 #6451] DEBUG -- : MONGODB | localhost:27017 | test.find | SUCCEEDED | 0.002601s
D, [2018-03-02T10:56:45.205325 #6451] DEBUG -- : MONGODB | localhost:27017 | test.find | STARTED | {"find"=>"system.namespaces", "filter"=>{"name"=>{"$not"=>/system\.|\$/}}}
 
input {
  mongodb {
    uri => 'mongodb://localhost/test'
    placeholder_db_dir => '/home/whb/Desktop/logstash/mongo/'
    placeholder_db_name => 'logstash_sqlite.db'
    collection => 'update'
    batch_size => 5000
  }
}

filter {
  date {
    match => [ "logdate", "ISO8601" ]
  }
}
output {
   elasticsearch {
     hosts => "http://localhost:9200"
     index => "bitcoin-prices"
  }
  stdout {}
}