Jackie-Jiang commented on pull request #8228:
URL: https://github.com/apache/pinot/pull/8228#issuecomment-1047362480
> > > At the moment, getNexBlock has a conditional split for all/partially
ordered columns (where computeAllOrdered is where all columns in select are
also in the order by if I understand correctly )
> > > If we introduce a case for when all orderBy columns are pre-sorted
(early termination case) then wouldn't we again have a
allOrdered/partialOrdered case within that as well?
> >
> >
> > No. If all the order-by columns are sorted, we can simply pick the first
`limit` docs without worrying about the optimization of partialOrdered case.
>
> May be we can get a slack call to resolve this quickly.
>
> The code "without this PR" looks like below
>
> ```
> if (_expressions.size() == _orderByExpressions.size()) {
> return computeAllOrdered();
> } else {
> return computePartiallyOrdered();
> }
> ```
>
> Here `computeAllOrdered` is where all columns in projection are in order
by clause. And, `computePartiallyOrdered` is where projection has more columns
that in order by clause.
>
> The two cases will also apply to the early terminate case. So with this
optimization we will have 4 cases.
>
> * computeAllOrderedWithEarlyTermination
> * computePartiallyOrderedWithEarlyTermination
> * computeAllOrdered
> * computePartiallyOrdered
>
> I am not sure this is any more readable that what I have.
What I am suggesting is something like:
```
if (allOrderByColumnsSorted()) {
return computeAllSorted();
} else if (_expressions.size() == _orderByExpressions.size()) {
return computeAllOrdered();
} else {
return computePartiallyOrdered();
}
```
If all order-by columns are sorted, we don't need to do the partially
ordered optimization, and the logic is all separated which is more clear and
can avoid unnecessary overhead
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