Hi,
After upgrading to XtraDB Cluster 5.7 (from 5.6), we noticed a severe performance decrease for select count(*) and sum() queries. Turns out there are several bug in 5.7, and some are already fixed.
For example Bug 81854 ([url]MySQL Bugs: #81854: Force index is skipped while executing select count(*)) has been fixed for the 5.7.18 release (that will hopefully appear soon).
Would Percona push these bug soon after being published? With not the newest Percona version is 5.7.14
Thanks,
Alex