zzwqqq commented on code in PR #5385:
URL: https://github.com/apache/calcite/pull/5385#discussion_r4534689674
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core/src/main/java/org/apache/calcite/sql2rel/CorrelateProjectExtractor.java:
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@@ -202,99 +187,77 @@ private static boolean isDirectFieldAccess(RexNode node,
CorrelationId id) {
return builder.build();
}
- /**
- * Traverses a plan and finds all simply correlated row expressions with the
specified id.
- */
- private static Set<RexNode> findCorrelationDependentCalls(CorrelationId
corrId, RelNode plan) {
- SimpleCorrelationCollector finder = new SimpleCorrelationCollector(corrId);
- plan.accept(new RelHomogeneousShuttle() {
- @Override public RelNode visit(RelNode other) {
- // Don't descend into a nested correlate that reuses this id: the refs
below belong to it.
- if (other instanceof Correlate
- && ((Correlate) other).getCorrelationId().equals(corrId)) {
- return other;
+ /** Applies the visitor within the specified correlation scope. */
+ private static RelNode visitCorrelationScope(RelNode root, CorrelationId id,
+ RexShuttle visitor) {
+ return root.accept(new RelHomogeneousShuttle() {
+ @Override public RelNode visit(RelNode rel) {
+ if (rel.getVariablesSet().contains(id)) {
+ if (rel instanceof Correlate) {
+ return visitChild(rel, 0, rel.getInput(0));
+ }
+ if (rel instanceof Project || rel instanceof Filter) {
+ return visitChildren(rel);
+ }
+ return rel;
}
- if (other instanceof Project || other instanceof Filter) {
- other.accept(finder);
- }
- return super.visit(other);
- }
- });
- return finder.correlations;
- }
-
- /**
- * Replaces all row expressions in the plan using the provided mapping.
- *
- * @param plan the relational expression on which we want to perform the
replacements.
- * @param mapping a mapping defining how to replace row expressions in the
plan
- * @return a new relational expression where all expressions present in the
mapping are replaced.
- */
- private static RelNode replaceExpressionsUsingMap(RelNode plan, Map<RexNode,
RexNode> mapping) {
- CallReplacer replacer = new CallReplacer(mapping);
- return plan.accept(new RelHomogeneousShuttle() {
- @Override public RelNode visit(RelNode other) {
- RelNode mNode = super.visitChildren(other);
- return mNode.accept(replacer);
+ final RelNode node = rel instanceof Project || rel instanceof Filter
+ ? rel.accept(visitor) : rel;
+ return visitChildren(node);
}
});
}
- /**
- * A collector of simply correlated row expressions.
+ /** Selects outermost deterministic computations over one correlation.
Review Comment:
Thanks. Each selected expression is stored in a `Map<RexNode, Integer>`. The
integer is its offset among the fields added to the left input. A Project
computes those fields. Selected occurrences in the right input are replaced
with `RexFieldAccess` references to the new fields. I've documented this in the
Javadoc.
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