Logstash input-jdbc work logic and last run sql_last_value

[vara0855 (Валера Носиков)]

Hello
I have ELK 6.3.2v.
Logstash-input-jdbc : v4.3.9

In my current configuration for the JDBC pipeline there are about 15-20 inputs with JDBC queries. Such inputs scheduled for run every minute -> "* * * * *" or every day.
For outputs I use elasticsearch-output.

I have a few questions about input works:

1. Why is the data in the file with the path last_run_metadata_path written only after the JDBC request is full completed?

2. What happens if the executing JDBC query fails with an error on some moment? Data in the last_run_metadata_path will be recorded?

3. Why the data in the file last_run_metadata_path is not recorded for each page of the read request if I set the jdbc_paging enabled.

4. What happens if the input does not have time to read all the data until the next scheduling execution ?

p.s. I experimented with jdbc_fetch_size, jdbc_page_size but they are not in the config example below
Example of one of the inputs :

input {
jdbc {
  id => "input_jdbc_order"
  jdbc_driver_library => "${LOGSTASH_JDBC_DRIVER:ojdbc6.jar}"
  jdbc_driver_class => "Java::oracle.jdbc.OracleDriver"
  jdbc_connection_string => "${LOGSTASH_JDBC_CONNECTION}"
  jdbc_user => "${LOGSTASH_JDBC_USER}"
  jdbc_password => "${LOGSTASH_JDBC_PASSWORD}"
  use_column_value => true
  tracking_column => tracking_number
  last_run_metadata_path => "${LOGSTASH_METADATA_PATH}/main/order"
  statement_filepath => "${LOGSTASH_JDBC_SQL_SCRIPTS_PATH}/main/order.sql"
  schedule => "* * * * *" #run every minute
  add_field => {
  	"[@metadata][type]" => "order"
  }
}
}

Regards