clock_gettime calls in sql_optimizer.cc account for ~4% of CPU time in the worst case

[mdcallag]

In the worst case (simple query such as fetch one row by PK) the usage of clock_gettime in sql_optimizer.cc accounts for ~4% of CPU time. The usage is here and is here.

Must this always be enabled?

[yoshinorim]

Could you try enable_optimizer_cputime_with_wallclock=on and enable_cputime_with_wallclock=on?

[mdcallag]

with that the overhead is ~3% of CPU time