Stamatis Zampetakis created CALCITE-4513:
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Summary: RelBuilder.aggregate destroys input traits when pruning
unused fields of project
Key: CALCITE-4513
URL: https://issues.apache.org/jira/browse/CALCITE-4513
Project: Calcite
Issue Type: Bug
Components: core
Affects Versions: 1.23.0
Reporter: Stamatis Zampetakis
Assignee: Stamatis Zampetakis
RelBuilder attempts to prune unused fields when the underlying input is a
project and the respective configuration
({{RelBuilder.Config#pruneInputOfAggregate}}) is enabled (CALCITE-3763). As a
result of this optimization a new project operator is introduced in the plan.
The new operator is created via {{Project#copy}} method but instead of
retaining or adapting the previous traitset a new one is created
(https://github.com/apache/calcite/blob/94502f51e6a12cd53cec88b39d21b4fec6070428/core/src/main/java/org/apache/calcite/tools/RelBuilder.java#L1922).
{code:java}
r = project.copy(cluster.traitSet(), project.getInput(), newProjects,
builder.build());
{code}
The main problem with that is that a {{HiveProject}} operator which used to be
in {{HiveConvention}} will be transformed to a {{HiveProject}} operator in
{{Convention.None}}. Obviously other traits (apart from {{Convention}})
potentially present in the operator are also lost after the transformation.
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