julianhyde commented on code in PR #2916:
URL: https://github.com/apache/calcite/pull/2916#discussion_r977348821
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core/src/main/java/org/apache/calcite/rel/rules/PruneEmptyRules.java:
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@@ -551,17 +529,15 @@ public interface JoinRightEmptyRuleConfig extends
PruneEmptyRule.Config {
// "select * from emp left join dept" is not necessarily empty if
// dept is empty
// join can be removed and take the left branch, all columns come
from dept are null
- List<RexNode> projects = new ArrayList<>(
- left.getRowType().getFieldCount() +
empty.getRowType().getFieldCount());
- List<String> columnNames = new ArrayList<>(
- left.getRowType().getFieldCount() +
empty.getRowType().getFieldCount());
- // left
- copyProjects(
- rexBuilder, left.getRowType(), join.getRowType(), 0, projects,
columnNames);
- // right
- addNullLiterals(rexBuilder, empty, projects, columnNames);
-
- RelNode project = call.builder().push(left).project(projects,
columnNames).build();
+ List<Pair<? extends RexNode, String>> projects =
+ Stream.concat(
+ getProjectStream(left.getRowType(), join.getRowType(), 0,
rexBuilder),
+ getNullLiteralStream(empty,
rexBuilder)).collect(Collectors.toList());
+
+ RelNode project = call.builder()
+ .push(left)
+ .project(Pair.left(projects), Pair.right(projects))
+ .build();
Review Comment:
I have a feeling that it could be even shorter if you use Guava's
`List.concat()` rather than `Stream.concat()`, and use `RelBuilder.fields()`.
You'll have to assign the `RelBuilder` to a variable.
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