A connection is a configuration for syncing data between a source and a destination. To setup a connection, a user must configure things such such as:
A catalog selection: which streams and fields to replicate from the source
Sync schedule: when to trigger a sync of the data
Syncs will be triggered by either:
A manual request (i.e: clicking the "Sync Now" button in the UI)
When a scheduled connection is first created, a sync is executed as soon as possible. After that, a sync is run once the time since the last sync (whether it was triggered manually or due to a schedule) has exceeded the schedule interval. For example, consider the following illustrative scenario:
October 1st, 2pm, a user sets up a connection to sync data every 24 hours.
October 1st, 2:01pm: sync job runs
October 2nd, 2:01pm: 24 hours have passed since the last sync, so a sync is triggered.
October 2nd, 5pm: The user manually triggers a sync from the UI
October 3rd, 2:01pm: since the last sync was less than 24 hours ago, no sync is run
October 3rd, 5:01pm: It has been more than 24 hours since the last sync, so a sync is run