Read the javadoc of RelBuilder.empty(). Does that solve your problem? Julian
> On Nov 7, 2017, at 7:01 AM, Vova Vysotskyi <[email protected]> wrote: > > Hi all, > > In CALCITE-1056 <https://issues.apache.org/jira/browse/CALCITE-1056> was > optimized planning by returning RelBuilder.empty() when the predicate in > the filter is always false. > > Drill can dynamically describe columns at runtime, but some of them, or > their actual types may be unknown at planning time. > > Drill is able to return column info for the queries that do not return any > results. But with the change which was made in CALCITE-1056 > <https://issues.apache.org/jira/browse/CALCITE-1056>, it becomes impossible > since for the cases when a predicate is always false, RelBuilder.empty() is > returned. > > Is it acceptable to make RelBuilder.filter() configurable to avoid > returning RelBuilder.empty()? > I propose to change condition on this line > <https://github.com/apache/calcite/blob/fb760a6f4e0cf8ccf92380dd676a72d00402d53e/core/src/main/java/org/apache/calcite/tools/RelBuilder.java#L921> > into *x.isAlwaysFalse() && simplify*. > Also, some other Hook may be created for this goal when we will decide to > use such approach. > > -- > Kind regards, > Volodymyr Vysotskyi
