Steps to reproduce:
1. Load TPCC data set (for the experiment I have used --tables=10 --scale=40) given my 24 cores VM.
2. Run the TPCC workload.
Retry (1) and (2) with 10.5 and 10.6. You will observe the significant performance difference.
check the graph for reference.
If you try to do (1) with 10.5 (loading with 10.5) and (2) with 10.6 you would see that performance is restored back to the original level as set by 10.5.
What is going wrong?
1. there have been multiple changes in the recent 10.6.5 timeframe (#25919) around stats recalculation. It has been observed that with 10.6.5 during/post-loading background stats calculation is not taking place. (This could be confirmed by querying mysql.innodb_table_stats post loading).
2. Behavior is intermittent and also could also get affected by the configuration of load and machine though there is no set pattern observed. [I was able to reproduce it majority of the times (9 out of 10 times). One suggestion to improve reproducibility: load the machine enough to keep CPU busy with loading of the data].