I had an interesting experience recently which I will share, as it may help you recover.
I recently transferred several websites from one hosting provider to another using plug-in backup tools which dumped the WordPress sites in a format that was readily importable/buildable on the new host servers. However, when I logged into the transferred websites, the websites seemed to have a variety of plug-in “idiosyncrasies” that were driving me in circles when trying to resolve. I deactivated and uninstalled various plug-ins to determine whether these were causing the problems, but I couldn’t make any headway at diagnosing exactly what was causing the problem.
Eventually, I got into cPanel and phpMyAdmin to look at the WordPress tables.
Here is what I discovered:
It seems that many, many plug-ins leave tables and records in the WordPress database when the plug-ins are deactivated (or uninstalled). This includes PODS, which leaves tables in the “options” table and the “postmeta” table. Depending on the plug-in, this residual data may play havoc should the plug-in be re-installed.
Once I deleted all references to non-existent plug-ins, and all plug-ins that I had deactivated, the “idiosyncrasies” disappeared. (Caveat emptor: I tend to “try out” plug-ins; hence, I had a lot of left-over data records and tables from uninstalled plug-ins.)
My big takeaway from the day I spent cleaning up the database was that leaving data behind in the database seems to be normal operating procedure for plug-ins, and in order to keep the database “clean,” one must manually check the database for left-over data. Checking the database can easily be accomplished by “export[ing]” the table as an .sql file, and reviewing it with a quality editor (such as Notepad++). PODS data may be found by searching the file for “pods.” Should you do this, ensure you make a backup of the database before making any changes.
Needless to say, keeping the database cleaned up is now one of my recurring tasks.
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This reply was modified 4 years, 10 months ago by Harry Hobbes.