10 May
2015
10 May
'15
1:28 p.m.
Hi, Sergey! On May 09, Sergey Vojtovich wrote:
Which may be fine, if MDL subsystem places only one lock in this case (iirc, it does). But what is cheaper - collapse identical schemas into one mdl request here (with Hash_set) or let mdl sort it out later? MDL doesn't eliminate them, but rather clones compatible requests. Performance wise it will be slower in certain cases, but since this is DDL is performance that important?
If it isn't, why are you eliminating Hash_set?
Because Hash_set was created for DML too. :(
I see. I believe it's rather unusual to have DDL that involves many tables, so fine, ok to push. Regards, Sergei