as I'm having some, let's say, "optimisation issues" with a multi source/channel replication slave, I was checking for "perf top" output to detect kernel function load anomalies.
The output shows a in my eyes high (17%-40%) overhead caused by btr_search_guess_on_hash.
[perf top]
Does somebody know if a high load on btr_search_guess_on_hash is a hint at mysql queries being badly optimised or an index or something missing? What am I looking for in order to optimise potential issues?
Thank you in advance!