[Plugin: Online Backup for WordPress] SQL Error and Primary Key

For the second problem, this is normal and can usually be ignored. It just means a plugin that isn’t designed very well.

You’ll find the FAQ here:
https://wordpress.backup-technology.com/FAQ

Here is the bit for the problem you posted – it’s quite a thorough explanation but I think everything is getting a refresh soon to make it all simpler and minimalist.

Because our plugin takes data from your tables section by section instead of all at once to prevent any problems with web servers that don’t like long running scripts, we need a method of distinguishing between what we have backed up already, and what we haven’t, in case the database contents change during the backup. We could lock the tables and prevent changes but this would not be a feasible approach for a constantly changing blog. So to get around the problem of changing data, we use the table PRIMARY key, which is a unique value in every row and allows us to remember exactly which rows we have already backed up.

However, some tables are poorly designed and do not have any PRIMARY key, so we do not have a unique value to distinguish between rows and we are forced to request a range of rows. What this means is that if a new row of information is inserted into the table at the beginning, and we are in the middle of a backup, when we ask for the range of rows “50-100”, we would instead receive what was previously rows “49-99” (the inserted row will make row 1 become row 2, and so on.) This will cause the backup to contain the same row twice. In a potentially worse scenario, if the first row is deleted while we are performing a backup, when we request rows “50-100” we would receive rows “51-101”! We would essentially miss row 50, and have no way of knowing or preventing this.

Because of this problem, we have made the plugin report this as a warning so that you are aware that should the table be consistently changing, the backup may not be completely consistent, and some rows may have been duplicated or lost.

Hi jnze,

Do you know the version of PHP your web host has? You might need to login the control panel to take a look.

Please could you email it to support “at” backup-technology “dot” co “dot” uk
I’ll watch the email. Post here when you’ve sent. I’ll get over to you a special version of the plugin you can try which will hopefully shed a bit more light on the problem.

Regards,

Jason.

Hi jnze,

Can you run another manual backup and let me know if you still end up with a 0 bytes file?

Also, are you running a manual download backup with encryption, or without encryption? (As in, does it give you a .enc file or a .zip file.)

Regards,

Jason

Hi jnze,

I haven’t found the email you sent I’m afraid. I’ve still produced a debug version for you to try. If you can email me again I can email it back to you.
support@backup-technology.co.uk

I’ll give you instructions in the email.

Thanks,

Jason