vlsi commented on a change in pull request #2187:
URL: https://github.com/apache/calcite/pull/2187#discussion_r502822379
##########
File path:
core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java
##########
@@ -906,6 +903,60 @@ void rename(RelNode rel) {
}
}
+ /**
+ * Checks whether a relexp has made any subset cheaper, and if it so,
+ * propagate new cost to parent rel nodes.
+ *
+ * @param rel Relational expression whose cost has improved
+ */
+ void propagateCostImprovements(RelNode rel) {
+ RelMetadataQuery mq = rel.getCluster().getMetadataQuery();
+ Map<RelNode, RelOptCost> propagateRels = new HashMap<>();
+ PriorityQueue<RelNode> propagateHeap = new PriorityQueue<>((o1, o2) -> {
+ RelOptCost c1 = propagateRels.get(o1);
+ RelOptCost c2 = propagateRels.get(o2);
+ if (c1.equals(c2)) {
+ return 0;
+ } else if (c1.isLt(c2)) {
+ return -1;
+ }
+ return 1;
+ });
+ propagateRels.put(rel, getCost(rel, mq));
+ propagateHeap.offer(rel);
+
+ while (!propagateHeap.isEmpty()) {
+ RelNode relNode = propagateHeap.poll();
+ RelOptCost cost = propagateRels.get(relNode);
+
+ for (RelSubset subset : getSet(relNode).subsets) {
+ if (relNode.getTraitSet().satisfies(subset.getTraitSet())) {
+ // Update subset best cost when we find a cheaper rel or the current
+ // best's cost is changed
+ if (cost.isLt(subset.bestCost)) {
Review comment:
It would be nice to reduce the nesting level with `continue`;
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
[email protected]
