There seems to be a system service unit localsearch-3.service. This unit fails every time i start my Laptop. According to journalctl, i get the message:
Could not create store: ambiguous column name: ROWID
What is this and how can i repair it?
I don’t have this .service file on my system, and I have no idea what it does, but you can use locate to find out which file it is (including its path), and then query pacman to find out where it comes from… 
locate localsearch-3.service
pacman -Qo /path/to/localsearch-3.service
Accoring to the man page:
localsearch-3 is not supposed to be run by the user since it is started by its .desktop file when the user logs in. It can also be started manually of course for debugging purposes. You can not run more than one instance of this at the same time.
localsearch-3 mines information about applications and files only.
As far as I know it’s part of Gnome. But I wouldn’t worry 'bout it if you don’t have any issues.
Edit:
For more:
Many thx. I could repair it with localsearch reset