I'm using MySQL 5.6 with about 5 databases on linux. I have scheduled daily full backups using mysqldump. All databases use InnoDB engine.
What I observe is that the backup size seems to vary everyday. This would make sense if the backup size keeps increasing but what is happening is randomly the backup size goes down.
I have confirmed with application teams that do not purge or delete data and I understand mysqldump is a logical representation of the data but how can backup size decrease randomly when there is no delete/truncate of data?