okumin commented on code in PR #6244:
URL: https://github.com/apache/hive/pull/6244#discussion_r2771782228
##########
ql/src/java/org/apache/hadoop/hive/ql/optimizer/stats/annotation/StatsRulesProcFactory.java:
##########
@@ -2030,6 +2030,18 @@ public Object process(Node nd, Stack<Node> stack,
NodeProcessorCtx procCtx,
}
}
+ // NDV=0 means join key statistics are unavailable - fall back to
joinFactor heuristic
+ if (allSatisfyPreCondition) {
+ for (int pos = 0; pos < parents.size(); pos++) {
+ ReduceSinkOperator parent = (ReduceSinkOperator)
jop.getParentOperators().get(pos);
+ List<String> keyExprs =
StatsUtils.getQualifedReducerKeyNames(parent.getConf().getOutputKeyColumnNames());
+ if (!satisfyPrecondition(parent.getStatistics(), keyExprs)) {
+ allSatisfyPreCondition = false;
+ break;
+ }
+ }
+ }
Review Comment:
@konstantinb Sorry for confusing you. This is a comment for myself. I took a
glance at this code, and it seems to be OK, but I have not dug into the entire
semantics of JoinStatsRule. I can't merge an OSS pull request with a very
optimistic imagination. So, I want to take a deep look again later. I'll write
this sort of info in my private note next time. Sorry
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