SUMMARY: Baloo is hopefully bluffing about indexing its index STEPS TO REPRODUCE: In a test username, one without many things to index, configure baloo to index hidden files balooctl config set hidden true and run balooctl monitor in a second window. Purge the index balooctl purge and watch... OBSERVED RESULTS You'll see "balooctl monitor" show Indexing modified files Indexing file content Indexing: /home/test/.local/share/baloo/index: Ok and also 'at regular intervals' Indexing modified files Indexing file content Indexing: /home/test/.local/share/baloo/index-lock: Ok EXPECTED RESULTS Gut feeling is that baloo should avoid its index SYSTEM INFORMATION Neon Testing Plasma : 5.21.3 Frameworks : 5.81.0 Qt : 5.15.2 ADDITIONAL INFORMATION Probably just noise :-) Don't see any evidence of a change to the index file when it is "indexed", I'm assuming the attempt is caught somewhere else in the process. Also not noticed any performance blips to say that baloo is read the full index file. Not clear if the file is read to determine the mimetype and (just maybe) there's a worry is that a 'read' of the index impacts the file locking. The lockfile is however reindexed at intervals (maybe every 45 to 50 seconds). That is, baloo notices that its index has been locked/released and indexes at the lockfile again, which locks/releases the index. Reported on the offchance that a nastier edge case is possible.
You told it to index it, so it does. Anyway, its harmless. It sees there is nothing to index, and continues with the next file.
I've no evidence that "it happens", but just to confirm that baloo isn't reading the index file? In the cases where "index" is a Gbyte or more, it could be something of a burden... I'm happy to add a .local/share/baloo exclusion but I feel it shouldn't be necessary.
LMDB files are not included in the shared-mime-info database, reported: https://gitlab.freedesktop.org/xdg/shared-mime-info/-/issues/168