The old wording talked about a "sync command", meaining fsync(), but it
was not very clear.
- Issue sync commands as soon as there is WAL data which has not been
- flushed yet. Also status packets are sent back to the server just after
- WAL data is flushed whatever --status-interval> is set to.
+ Flush the WAL data to disk immediately after it has been received. Also
+ send a status packet back to the server immediately after flushing,
+ regardless of --status-interval>.