Hi, There was a Calcite JIRA (CALCITE-2718 <https://issues.apache.org/jira/browse/CALCITE-2718>) which describes this issue exactly. There are also some other rules which would miss alias, so it's safe to reference fields by position instead of name. Hope it helps.
[1] https://issues.apache.org/jira/browse/CALCITE-2718 Best, Jing Zhang JiaTao Tao <[email protected]> 于2021年11月26日周五 上午11:03写道： > In fact, calcite's rule doesn't care about alias, so it may lose alias when > transforming. > > Regards! > > Aron Tao > > > Yanjing Wang <[email protected]> 于2021年11月24日周三 下午2:47写道： > > > Hi, team > > I'm using ProjectRemoveRule to simplify my logical plan, But the plan > > sometimes miss its project alias, I find the rule hasn't checked the > alias > > for project row type identity equation, so I think it may be a bug, I > have > > tried to reproduce the problem, but I failed to build two projects. > > > > I have tried the following but the plan always ignores the alias: > > > > final Function<RelBuilder, RelNode> relFn = b -> { > > RelNode plan = b.scan("EMP") > > .project( > > b.field("DEPTNO"), > > b.field("ENAME") > > ) > > .project( > > b.alias(b.field(0), "DEPTNO_ALIAS"), > > b.alias(b.field(1), "ENAME_ALIAS") > > ) > > .build(); > > return plan; > > }; > > > > relFn(relFn) > > .withRule( > > CoreRules.PROJECT_REMOVE) > > .withRelBuilderConfig(b -> b.withBloat(-1)) > > .check(); > > > > > > So I resort to modifying existing test case to reproduce, I change > > the testUnionMergeRule test case in RelOptRulesTest.java. I change its > > final projection *** to *name as ename, deptno as edeptno*, > > and the plan miss the alias again. I think the hep rules shouldn't remove > > the alias which are output column label. > > >
