morrySnow commented on a change in pull request #8695:
URL: https://github.com/apache/incubator-doris/pull/8695#discussion_r836352339
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File path:
fe/fe-core/src/main/java/org/apache/doris/planner/JoinCostEvaluation.java
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@@ -147,7 +149,7 @@ public long constructHashTableSpace() {
Math.pow(1.5, (int) ((Math.log((double)
rhsTreeCardinality/4096) / Math.log(1.5)) + 1)) * 4096;
double nodeOverheadSpace = nodeArrayLen * 16;
double nodeTuplePointerSpace = nodeArrayLen * rhsTreeTupleIdNum * 8;
- return Math.round((bucketPointerSpace + (double) rhsTreeCardinality *
rhsTreeAvgRowSize
+ return Math.round((bucketPointerSpace + (double) rhsTreeCardinality *
rhsTreeAvgRowSize * COMPRESSION_RATIO
Review comment:
yes, you are right. multiplying by a fixed ratio is not accurate. But
the error in data size is not only just introduced by compressed ratio.
Since, we don't have accurate statistics now, the average row size and
cardinality are also inaccurate.
So the compression ratio of 5 is used here, based on observations of
imported data to Doris.
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