Besides the full import functionality, Pacemaker Community Edition (CE) also supports delta import functionality.
The delta import supports SKUs that is not part of one of the actual CSV files like listed below
all link types (up-sell, cross-sell + related)
In contrast to a full import, which requires the following invocation of the appropriate indexers, after a delta import, the delta indexing functionality takes care for the necessary index updates.
The delta indexer can not be started on the command-line. Instead, it’ll be initiated by the default Magento CRON job.