[GitHub] [doris] englefly commented on a diff in pull request #20642: [tpcds](nereids) estimate distribution cost by byte size instead of row count

["englefly (via GitHub)" <gi...@apache.org>]

englefly commented on code in PR #20642:
URL: https://github.com/apache/doris/pull/20642#discussion_r1226270669


##########
fe/fe-core/src/main/java/org/apache/doris/nereids/cost/CostModelV1.java:
##########
@@ -161,27 +161,27 @@ public Cost visitPhysicalPartitionTopN(PhysicalPartitionTopN<? extends Plan> par
     @Override
     public Cost visitPhysicalDistribute(
             PhysicalDistribute<? extends Plan> distribute, PlanContext context) {
+        int kBytes = 1024;
         Statistics childStatistics = context.getChildStatistics(0);
         DistributionSpec spec = distribute.getDistributionSpec();
+        int beNumber = ConnectContext.get().getEnv().getClusterInfo().getBackendsNumber(true);
+        beNumber = Math.max(1, beNumber);
+        double dataSize = childStatistics.computeSize() / kBytes; // in K bytes
         // shuffle
         if (spec instanceof DistributionSpecHash) {
             return CostV1.of(
                     0,
                     0,
-                    childStatistics.getRowCount());

Review Comment:
   ok, let's do it in next pr



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