Need clarification on sql_last_value used in Logstash configuration

Hi All i am using below code for indexing data from MSSql server to elasticsearch but i am not clear about this sql_last_value.

input {
jdbc {
jdbc_driver_library => ""
jdbc_driver_class => "com.microsoft.sqlserver.jdbc.SQLServerDriver"
jdbc_connection_string => "jdbc:sqlserver://xxxx:1433;databaseName=xxxx;"
jdbc_user => "xxxx"
jdbc_paging_enabled => true
tracking_column => modified_date
tracking_column_type => "timestamp"
use_column_value => true
jdbc_password => "xxxx"
clean_run => true
schedule => "*/1 * * * *"
statement => "Select * from [dbo].[xxxx] where modified_date >:sql_last_value"
}
}

filter {
if [is_deleted] {
        mutate {    
            add_field => {
                "[@metadata][elasticsearch_action]" => "delete"
            }
        }
        mutate {
            remove_field => [ "is_deleted","@version","@timestamp" ]
        }
    } else {
        mutate {    
            add_field => {
                "[@metadata][elasticsearch_action]" => "index"
            }
        }
        mutate {
            remove_field => [ "is_deleted","@version","@timestamp" ]
        }
    } 
}

output {
elasticsearch {
hosts => "xxxx"
user => "xxxx"
password => "xxxx"
index => "xxxx"
action => "%{[@metadata][elasticsearch_action]}"
document_type => "_doc"
document_id => "%{id}"

}
stdout { codec => rubydebug }
}

Where this sql_last_value stored and how to view that physically? Is it possible to set a customized value to sql_last_value?

Could any one please clarify on above queries?

The sql_last_value is stored in the file called .logstash_jdbc_last_run and according to the docs it is stored in $HOME/.logstash_jdbc_last_run. The file itself contains the timestamp of the last run and it can be set to a specific value.

You should define the last_run_metadata_path parameter for each single jdbc_input_plugin and point to a more specific location, as all running jdbc_input_plugin instances will share the same .logstash_jdbc_last_run file by default and potentially lead into unwanted results.