29 Apr
2014
29 Apr
'14
9:44 p.m.
Hi, Anshu! On Apr 30, Anshu Avinash wrote:
You've looked at the code, what do you think? Do you understand how different parts of this feature fit together? We can start from just one constant (global or per-engine) and see how it'll work.
I had started exploring tmptable_create_cost. In sql/sql_const.h: HEAP_TEMPTABLE_CREATE_COST is defined to be 2.0 and DISK_TEMPTABLE_CREATE_COST as 40.0. As discussed on irc with serg, I'll start to profile this constant (which I have not started yet).
Note, that you shouldn't profile anything yourself. Instead, the goal is to have profiling code built into the server and it should profile and adjust these constants automatically. Regards, Sergei