How to keep my entries ordered as in my file

[czem (Caio Zem)]

I'm ingesting a log file with Filebeat and sending to my ElasticSearch through Logstash. My log file has the following pattern:

Timestamp - TransactionId - Header (Username)
Timestamp - TransactionId - Events (This line may repeat multiple times)
Timestamp - TransactionId - Footer

The timestamp doesn't include milliseconds and sometimes the timestamp may repeat for the same transaction. I would like to make sure the order I see in Kibana is the same as in the file.

Today I use Aggregate to distribute fields I have in my header to all log entries. I've tried to create a field called "milliseconds" in the aggregation and increment it for each subsequent line that got matched. My intention was to add this field to the timestamp latter.

if [sync_type] == "start"
{
	aggregate {
		task_id => "%{transaction_id}"
		code => "
			map['milliseconds'] = 0
		"
		map_action => "create"
	}
}
else if [sync_type] == "end"
{
	aggregate {
		task_id => "%{transaction_id}"
		code => "
			event.set('milliseconds', map['milliseconds'] + 1)
		"
		map_action => "update"
		end_of_task => true
		timeout => 120
	}
}
else
{
	aggregate {
		task_id => "%{transaction_id}"
		code => "
			event.set('milliseconds', map['milliseconds'] + 1)
		"
		map_action => "update"
	}
}

It didn't work... every line remains with the fields "milliseconds" as 1.

Any idea of how I can make this work?

Thanks.