jinxing64 commented on a change in pull request #1500: [CALCITE-3405] Prune
columns for ProjectableFilterableTable when Proj…
URL: https://github.com/apache/calcite/pull/1500#discussion_r334742410
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File path:
core/src/main/java/org/apache/calcite/rel/rules/ProjectTableScanRule.java
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@@ -103,30 +106,47 @@ protected static boolean test(TableScan scan) {
protected void apply(RelOptRuleCall call, Project project, TableScan scan) {
final RelOptTable table = scan.getTable();
assert table.unwrap(ProjectableFilterableTable.class) != null;
- if (!project.isMapping()) {
- return;
- }
- final Mappings.TargetMapping mapping = Project.getPartialMapping(
- project.getInput().getRowType().getFieldCount(),
- project.getProjects());
- final ImmutableIntList projects;
- final ImmutableList<RexNode> filters;
+ final List<Integer> selectedColumns = new ArrayList<>();
+ project.getProjects().forEach(proj -> {
+ proj.accept(new RexVisitorImpl<Void>(true) {
+ public Void visitInputRef(RexInputRef inputRef) {
+ if (!selectedColumns.contains(inputRef.getIndex())) {
+ selectedColumns.add(inputRef.getIndex());
+ }
+ return null;
+ }
+ });
+ });
Review comment:
Well, I was also thinking about this ~
The concern here is that the order of selected fields will be lost if using
`InputFinder` and record by bit set.
If the order of selected fields for pushing down is lost, we have to add
another `Project` on top of `BindableTableScan` for adjusting.
`ScannableTableTest#testPushSimpleMappingProject` is to test such case.
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