Fsyncs can be combined. You don‘t need 40k fsyncs for 40k inserts. While one fsync is running multiple inserts are queued and fsnced together when e.g. the last

Fsyncs can be combined. You don‘t need 40k fsyncs for 40k inserts. While one fsync is running multiple inserts are queued and fsnced together when e.g. the last fsync is done.