Jdbc_streaming named parameters

[cerutidavide (Davide)]

I am pretty new to ELK, I have a problem with jdbc_streaming filter plugin.
It seems that parameters is not properly set and my query doesn't work.

filter {

jdbc_streaming {
jdbc_user => ""
jdbc_password => ""
jdbc_driver_class => "Java::oracle.jdbc.driver.OracleDriver"
jdbc_driver_library => "/home/logstash/ingestion_servizi/ojdbc5.jar"
jdbc_connection_string => "jdbc:oracle:thin:@//host:port/databasesid"
statement => "select a as ttype,name from databasesid.AAA WHERE AAA.NAME = :xx"
parameters => { "xx" => "servername" }
target => "devicetype4"
}

already verified that query return values from database.
If I remove WHERE clause result is correct and devicetype4 is properly populated with an array matching values from database column.
Any help?
Thanks
Davide