JDBC input scheduling question

Elastic Stack Logstash
1

I added a jdbc input to my config files:

input {
  jdbc {
    jdbc_driver_library => "/usr/share/java/postgresql94-jdbc.jar"
    jdbc_driver_class => "org.postgresql.Driver"
    jdbc_connection_string => "jdbc:postgresql://psqlhost:5432/mydb"
    jdbc_user => "myuser"
    jdbc_password => "mypass"
    jdbc_validate_connection => "true"
    # schedule => "* 6 * * *"
    statement => "select stuff from table"
    add_field => {
      "index" => "jdbc"
      "type" => "RequestCreated"
    }
  }
}

And the following ES output config:

output {
  if [type] == "RequestCreated" {
    elasticsearch {
      hosts => [ "localhost" ]
      index => "%{index}-%{+YYYY.MM.dd}"
      document_type => "%{type}"
      document_id => "%{requestid}"
    }
  }
}

I also created an index using a field from my DB table that gets updated every time a record gets updated.

As far as I can understand, this SELECT should only run once, but I keep seeing new data in Kibana. Where is it coming from? Is there a default schedule? Documentation says when no schedule is specified, SELECT will only run on logstash restart.

Thanks.