vineetgarg02 commented on a change in pull request #603: HIVE-21633
URL: https://github.com/apache/hive/pull/603#discussion_r279137177
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File path:
ql/src/java/org/apache/hadoop/hive/ql/optimizer/stats/annotation/StatsRulesProcFactory.java
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@@ -1524,6 +1531,77 @@ public Object process(Node nd, Stack<Node> stack,
NodeProcessorCtx procCtx,
return null;
}
+ /**
+ * If possible, sets the min / max value for the column based on the
aggregate function
+ * being calculated and its input.
+ */
+ private static void computeAggregateColumnMinMax(ColStatistics cs,
HiveConf conf, AggregationDesc agg, String aggType,
+ Statistics parentStats) throws SemanticException {
+ if (agg.getParameters() != null && agg.getParameters().size() == 1) {
+ ColStatistics parentCS = StatsUtils.getColStatisticsFromExpression(
+ conf, parentStats, agg.getParameters().get(0));
+ if (parentCS != null && parentCS.getRange() != null &&
+ parentCS.getRange().minValue != null &&
parentCS.getRange().maxValue != null) {
+ long valuesCount = agg.getDistinct() ?
+ parentCS.getCountDistint() :
+ parentStats.getNumRows() - parentCS.getNumNulls();
+ Range range = parentCS.getRange();
+ // Get the aggregate function matching the name in the query.
+ GenericUDAFResolver udaf =
+
FunctionRegistry.getGenericUDAFResolver(agg.getGenericUDAFName());
+ if (udaf instanceof GenericUDAFCount) {
+ cs.setRange(new Range(0, valuesCount));
Review comment:
Assuming range represent the min,max possible value for the expression is
this calculation correct?
Lets say there are 1M numRows and count distinct is 2 and count aggregate is
distinct, this will set the range to (0,2) but it should be (0, 1/2M).
No? Or did I miss-understand range
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