konstantinb commented on code in PR #6505:
URL: https://github.com/apache/hive/pull/6505#discussion_r4475461858
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ql/src/java/org/apache/hadoop/hive/ql/optimizer/stats/annotation/StatsRulesProcFactory.java:
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@@ -558,18 +558,25 @@ private long evaluateInExpr(Statistics stats,
ExprNodeDesc pred, long currNumRow
factor *= children.size() - 1;
}
for (int i = 0; i < columnStats.size(); i++) {
- long dvs = columnStats.get(i) == null ? 0 :
columnStats.get(i).getCountDistint();
+ ColStatistics cs = columnStats.get(i);
+ long dvs = cs == null ? -1L : cs.getCountDistint();
if (dvs == 0) {
- factor *= 0.5;
- continue;
+ // verified zero distinct values: IN cannot match any row
+ factor = 0;
+ break;
Review Comment:
Keeping the clamp is intentional: `hive.stats.filter.in.min.ratio` is an
opt-in floor for IN estimates without a usable value range, and a stored NDV of
0 is the kind of estimate it protects against.
[17bccf8](https://github.com/apache/hive/pull/6505/commits/17bccf8d22) rewrites
the comment that overstated this and pins the interaction in
`TestStatsRulesProcFactory`.
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