What does ingestion time mean in CloudWatch

Question

In the structure of an event of Cloudwatch :

'events': [
        {
            'logStreamName': 'string',
            'timestamp': 123,
            'message': 'string',
            'ingestionTime': 123,
            'eventId': 'string'
        },
    ]

What does ingestionTime mean ?

In this doc they are saying :

ingestionTime

The time the event was ingested.

Which I find still unclear.

Answer 1

There are two timestamp fields, here.

The timestamp is the time the event was said to have occurred, according to the message that was sent to CloudWatch.

The ingestionTime is the time CloudWatch actually received the message about the event.

The difference between the two -- assuming all clocks are accurate -- is the delay between when the event occurred and when CloudWatch received and "ingested" (was fed, ate, consumed) the message about the event.