The hint can be used to specify the degree of parallelism (DOP), MIN/MAX memory allocated for the operator. In that case, we need to keep them in the physical operators. But I am not sure whether there are downstream projects that are using hints for physical resource.
On 2021/05/19 17:05:44, Julian Hyde <jhyde.apa...@gmail.com> wrote: > Sure, there’s a slot to hold the hints. But is there a benefit to keeping > them in the physical algebra? There is certainly a cost to storing them, > propagating them, fixing them up as we apply rules. > > The main source of hints is formatted comments in the SQL. As we get further > from the SQL source and the AST, the benefit decreases. > > Danny, > > Were you envisioning hints being propagated into physical algebra? There’s no > explicit mention in > https://docs.google.com/document/d/1mykz-w2t1Yw7CH6NjUWpWqCAf_6YNKxSc59gXafrNCs/edit > > <https://docs.google.com/document/d/1mykz-w2t1Yw7CH6NjUWpWqCAf_6YNKxSc59gXafrNCs/edit> > or https://issues.apache.org/jira/browse/CALCITE-482 > <https://issues.apache.org/jira/browse/CALCITE-482>. > > Julian > > > > On May 18, 2021, at 7:49 PM, JiaTao Tao <taojia...@gmail.com> wrote: > > > > Hi Julian > > > > When hints were introduced, was that part of the plan? > > > > "hint" is a field in the base class, so the type of the node doesn't matter > > > > public abstract class Project extends SingleRel implements Hintable { > > //~ Instance fields > > -------------------------------------------------------- > > > > protected final ImmutableList<RexNode> exps; > > > > protected final ImmutableList<RelHint> hints; > > > > > > And in RelBuilder#project, we just construct a project without > > hints(ImmutableList.of()), so it will lose hints too. > > > > public RelBuilder project(Iterable<? extends RexNode> nodes, > > Iterable<? extends @Nullable String> fieldNames, boolean force) { > > return project_(nodes, fieldNames, ImmutableList.of(), force); > > } > > > > > > > > Regards! > > > > Aron Tao > > > > > > Julian Hyde <jhyde.apa...@gmail.com> 于2021年5月19日周三 上午12:30写道： > > > >> Do we really need hints in physical operators? When hints were introduced, > >> was that part of the plan? > >> > >> Julian > >> > >>> On May 17, 2021, at 11:50 PM, JiaTao Tao <taojia...@gmail.com> wrote: > >>> > >>> Hi > >>> Recently, I'm integrating Calcite's hint into our system, and I've found > >>> the Enumerable rules just throw the hint info(ImmutableList.of()) away: > >>> > >>> public EnumerableProject( > >>> RelOptCluster cluster, > >>> RelTraitSet traitSet, > >>> RelNode input, > >>> List<? extends RexNode> projects, > >>> RelDataType rowType) { > >>> super(cluster, traitSet, ImmutableList.of(), input, projects, > >> rowType); > >>> assert getConvention() instanceof EnumerableConvention; > >>> } > >>> > >>> > >>> Regards! > >>> > >>> Aron Tao > >> > >
