Hi,
I just successfully upgraded my mariadb 10.1 database (+ nextcloud 12) for 4-byte character support according to: Enabling MySQL 4-byte support â Nextcloud 12 Server Administration Manual 12 documentation
File format needed to be changed to barracuda as expected, altering the tables worked fine, as well as adding the setting to config.php and occ maintenance:repair. So 
for admin manual about this!
Afterwards I just recognized that my database size was reduced from ~265 MB to ~123 MB. I am wondering what exactly is the reason for this. Does barracuda just provide that less database sizes or was it some cleanup included into occ maintenance:repair?
After the database table update the following steps show up:
âĻ
- Change collation for oc_federated_reshares âĻ
- Change row format for oc_polls_dts âĻ
- Change collation for oc_polls_dts âĻ
- Repair mime types
- Clean tags and favorites
- 0 tags of deleted users have been removed.
- 0 tags for delete files have been removed.
- 0 tag entries for deleted tags have been removed.
- 0 tags with no entries have been removed.
- Repair invalid shares
- Remove shares of a users root folder
- Move .step file of updater to backup location
- Add move avatar background job
- Repair step already executed
- Add preview cleanup background jobs
- Fix potential broken mount points
- No mounts updated
- Repair language codes
- Install new core bundle components
- Repair invalid paths in file cache
- Rename folder with user specific keys
I mean I am totally happy with this. I am just wondering if, whatever lead to this, could be added as sort of tweak hint or cron background job or something 
.