Domino 12.0.1 includes an interesting enhancement to the compact task options. Together with the options -c and -X, -RESTARTensures that a compact that terminates because the limit set with -X is exceeded continues at exactly the same point during the next run. This ensures that even large files are compressed, which at the moment would never be fully compressed due to exceeding the time limit.

load compact -c -X 2 -restart db.nsf

compresses the file db.nsf with copy-style compact, but stops the compression after 2 minutes. In the file system you can see a db.restart file.

If the compression is stopped after 2 minutes, then the db.restart file remains.
During the next run, more data is copied from db.nsf to db.restart. This is repeated until db.nsf is completely compressed.
Then db.nsf is renamed to db.orig, and db.restart is renamed to db.nsf.
Finally, db.orig is deleted. This completes the compression.

It is important to know that the –RESTART option can also be used together with the -REPLICA option. But there it has a completely different function.

DBMT uses only the -c option for the compact. If DBMT determines that the database would be added to the dbmt_compact_filter.ind file if it exceeds the timelimit, it passes in the –RESTART option.

Here is some additional information that is not (yet) documented.

Compact –RESTART requires active transaction logging. An enhancement request is pending at HCL, which issues a corresponding message on the Domino Server console if transaction logging is disabled in the advanced properties of an application. The change will probably not come until Domino 12.0.2.

Compact –RESTART currently only works in case the compression is aborted after reaching the time limit. In other cases (server crash, termination of the compact task) the .restart file is deleted. Again, I have submitted an enhancement request to extend the functionality accordingly. Also this change will probably not come until Domino 12.0.2.