Because of fast SSDs, I don’t use any type of file indexing anymore. I always search with find and grep on the command line anyway. Because of this, one of the first things I did after starting KDE was what you’re asking for: disable Baloo, and uninstall it, if possible.
First, I put this in my /home/$USER/.config/baloofilerc (a command like »balooctl disable« would do that as well):
[Basic Settings]
Indexing-Enabled=false
Log out, log in, and you should be set.
If you like to disable Baloo for all users, I think you could do the same in /etc/xdg/baloofilerc (not really sure whether the syntax in both rc files is the same though).
As long as Baloo is installed, you can check the storage space it occupies with …
balooctl indexSize
(Because I stopped it right after my first login, the sizes were negligible.)
Then I tried to uninstall anthing to do with file indexing, but due to a few dependencies with KDE/Plasma/Dolphin/XDG and whatnot, I ended up keeping the following packages around:
▶ **rpm -qa | grep -i baloo**
baloo5-widgets-17.12.3-lp150.1.2.x86_64
baloo5-imports-5.45.0-lp150.2.1.x86_64
libKF5Baloo5-5.45.0-lp150.2.1.x86_64
libKF5BalooEngine5-5.45.0-lp150.2.1.x86_64
▶ _
Four packages which zypper and YaST wanted to subbornly install again I marked »taboo« in YaST (»locked« in zypper-speak):
▶ **zypper ll | grep -i baloo**
20 | baloo5-imports-lang | package | (any)
21 | baloo5-kioslaves | package | (any)
22 | baloo5-widgets-lang | package | (any)
134 | libKF5BalooEngine5-lang | package | (any)
Never heard of Recoll before, but I’ll keep it in mind if I ever need a file(-contents) indexer again. Cheers!