You might face an increase of the file
Here few commands that allows you to dig within the db, and clean up some rows, reducing its size.
Open the db:
Now, check all the tables available:
bans fail2banDb jails logs
Generally, the “bans” table is the one that uses more space. You can check the content of this table using some SELECT statements like:
sqlite> SELECT * FROM bans limit 1;
With this, you can check one single row, and all its parts and content.
If you identify, for example, that there are very old entries (in my case, entries from 2 years ago, from 2018 and 219), you can trim all those entries with this command:
sqlite> DELETE FROM bans WHERE DATE(timeofban, 'unixepoch') < '2020-01-01'; VACUUM;
After running the above command, I got my db shrank.
A restart of fail2ban services will reload the db and release the space of the previous db.