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 >>
