DB only records meta data about files ... no blob records that would be representations of files that have been uploaded to Moodle. So don't think DB is an issue here.
After the edits to php.ini and restart of apache, the phpinfo in Moodle now shows the values for 2G. Is that correct?
.htaccess files can override what one puts in php.ini ... so really only one method for controlling this need be done. I use .htaccess to override defaults - max size 2 Gigs ... in some apps on same server I'd have to use .htaccess files to set that lower in some areas of the other apps - like a WordPress Uploads directory.
There is one other setting related and it's with Apache ... limitrequestbody ... normally it's set to unlimited.
http://www.cyberciti.biz/faq/apache-limiting-upload-size/
When one sets via php/.htaccess the setting then applies to all users that can upload (mentioned that cause it's something of which to be aware).
There's an alternative method for uploading files to an area/space on the server where Moodle could see it - File System Repo.
First, make a directory in moodledata/repository/ that's reflective of purpose ... like 'largerestores'.
Make the directory readable/writable by the apache user/group.
Then in Moodle, turn on File System Repos.
https://docs.moodle.org/31/en/Repositories
Go to any course and setup the file system repo by a label that points to the 'largerestores' directory.
To get large .mbz backups there, use 'secure copy' ... from a Linux/Mac, one can use the 'scp' command as the root user for the Moodle server to upload a file to moodledata/repository/largerestores/ Think Windows has a thing called WinSCP you'd need to install.
Since you are using scp that's NOT php and thus not restricted/limited by anything Moodle which runs under PHP.
Would limit who knows the login/password to server that would allow scp copies of large files.
'spirit of sharing', Ken