The man page of logrotate says that:

It can be used when some program cannot be told to close its logfile
and  thus  might  continue writing to the previous log file for some
time.

I'm confused by this. If a program cannot be told to close its logfile, it will continue to write forever, not for sometime. If the compression is postponed to next rotation cycle, the program continues to write to that file even after the next rotation cycle. How is postponing solving the problem?

My understanding is that copytruncate should be used when a program cannot be told to close the logfile. I'm aware that some data written to the logfile gets lost when the copy is in progress.

I was looking at the logrotate file for couchdb, and it had both copytruncate and delaycompress options.

/usr/local/couchdb-1.0.1/var/log/couchdb/*.log {
   weekly
   rotate 10
   copytruncate
   delaycompress
   compress
   notifempty
   missingok
}

It looks like there is no point using delaycompress when copytruncate is already there. What am I missing?