Allowed memory size exhausted

I’m receiving the following error, literally logged this error 111,631 times. The guy who administers this site is getting WSoDed when he’s in the wp-admin dashboard. As far I know, users don’t see this error. The log shows that this error happens several times an hour every day since 2017.

This is the error:

[08-Jan-2019 20:09:30 UTC] PHP Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 31457280 bytes) in /home1/ab44635/public_html/wp-includes/wp-db.php on line 1323

If this was a plugin causing the problem, I’d expect that we’d see something here about a plugin, but this looks like it might be a problem with the database needs more memory more than anything else, but I’m not a WP pro.

Please advise on what you think the best thing to do here will be.