I have been using Austin Matzko’s WordPress Database Backup plugin from shortly after I moved to WordPress about 3 years ago. Until the last week, it has been working perfectly on all my blogs where I use it. I have it set to email me daily the backup of my wordpress tables for each blog. That way I have a backup not stored on my server in case of emergencies.
However, I recently updated it to the new version on all blogs and at the same time it stopped sending me backup emails from this blog. It was working fine from the others, just not this one. I ran a backup manually and watched it create the backup, then instead of zipping it up and emailing, it just stopped.
I left Austin a message on his support forum and he responded the same day. I only saw the response when I checked today. While looking at the size of the backup files to answer one of his questions, I discovered that the size of the backup files were growing on a daily basis, by a significant amount. This caused me to check the size of the database tables that were being backed up.
The comments and commentmeta tables were a lot larger than I would have expected; then it hit me – spam comments! I have deleted over 1500 spam and optimised the tables and now the backup is working again. I’ll just have to keep an eye on the spam.