maheshk114 commented on a change in pull request #1147:
URL: https://github.com/apache/hive/pull/1147#discussion_r460001925
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File path:
ql/src/java/org/apache/hadoop/hive/ql/optimizer/stats/annotation/StatsRulesProcFactory.java
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@@ -2606,6 +2607,17 @@ private long computeFinalRowCount(List<Long>
rowCountParents, long interimRowCou
// max # of rows = rows from left side
result = Math.min(rowCountParents.get(joinCond.getLeft()), result);
break;
+ case JoinDesc.ANTI_JOIN:
+ long leftRowCount = rowCountParents.get(joinCond.getLeft());
+ if (leftRowCount < result) {
+ // Ideally the inner join count should be less than the left row
count. but if its not calculated
+ // properly then we can assume whole of left table will be
selected.
+ result = leftRowCount;
Review comment:
This case will come if the stats are not proper. So to be on safer side,
i assume that all rows from the left side will be projected. That is the max
value. If set it to 0, it should not trigger some re-write, assuming the join
result is empty.
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