davidradl commented on code in PR #27328:
URL: https://github.com/apache/flink/pull/27328#discussion_r2598139776
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flink-table/flink-table-planner/src/main/java/org/apache/flink/table/planner/plan/utils/FlinkRelUtil.java:
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@@ -122,6 +135,43 @@ public static boolean isMergeable(Calc topCalc, Calc
bottomCalc) {
return mergeable(topInputRefCounter, topInputRefs, bottomProjects);
}
+ private static boolean functionResultShouldBeReused(
+ List<? extends RexNode> topProjectList, List<? extends RexNode>
bottomProjectList) {
+ Set<Integer> indexSet = new HashSet<>();
+ for (int i = 0; i < bottomProjectList.size(); i++) {
+ RexNode project = bottomProjectList.get(i);
+ if (project instanceof RexCall
+ && SqlKind.FUNCTION.contains(((RexCall)
project).op.getKind())
+ && ((RexCall) project).op.isDeterministic()) {
Review Comment:
I do not know this area very well, just to check my understanding
- why are we calling the rexNodes projects?
- I assume that `isDeterministic` implies that for a given input you get
the same output. If there are non deterministic function in the list of
projects, this could imply we cannot use the out for it. Is it safe to reuse
the results if there are non deteministic projects? What would it mean to
re-use the results when there are any deterministic projects?
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