Em qua., 14 de jul. de 2021 às 22:22, David Rowley <dgrowleyml@gmail.com> escreveu:
On Thu, 15 Jul 2021 at 12:30, Ranier Vilela <ranier.vf@gmail.com> wrote: > > Em qua., 14 de jul. de 2021 às 21:21, David Rowley <dgrowleyml@gmail.com> escreveu: >> But, in v8 there is no additional branch, so no branch to mispredict. >> I don't really see how your explanation fits. > > In v8 the branch occurs at : > + if (ExecGetResultType(outerPlanState(sortstate))->natts == 1)
You do know that branch is in a function that's only executed once during executor initialization, right?
There's a real difference between v8 and v6, if I understood correctly.
v6 the branches is per tuple:
+ if (tupDesc->natts == 1)
v8 the branches is per state:
+ if (ExecGetResultType(outerPlanState(sortstate))->natts == 1)
I think that a big different way to solve the problem.
Or am I getting it wrong?
If the sortstate number of attributes is equal to 1, is it worth the same for each tuple?
