yupeng9 commented on a change in pull request #7630:
URL: https://github.com/apache/pinot/pull/7630#discussion_r735715494
##########
File path:
pinot-core/src/main/java/org/apache/pinot/core/query/aggregation/function/DistinctCountHLLAggregationFunction.java
##########
@@ -326,6 +375,54 @@ public Long extractFinalResult(HyperLogLog
intermediateResult) {
return intermediateResult.cardinality();
}
+ /**
+ * Returns the dictionary id bitmap from the result holder or creates a new
one if it does not exist.
+ */
+ protected static RoaringBitmap getDictIdBitmap(AggregationResultHolder
aggregationResultHolder,
+ Dictionary dictionary) {
+ DistinctCountHLLAggregationFunction.DictIdsWrapper dictIdsWrapper =
aggregationResultHolder.getResult();
+ if (dictIdsWrapper == null) {
+ dictIdsWrapper = new
DistinctCountHLLAggregationFunction.DictIdsWrapper(dictionary);
+ aggregationResultHolder.setValue(dictIdsWrapper);
+ }
+ return dictIdsWrapper._dictIdBitmap;
+ }
+
+ /**
+ * Returns the dictionary id bitmap for the given group key or creates a new
one if it does not exist.
+ */
+ protected static RoaringBitmap getDictIdBitmap(GroupByResultHolder
groupByResultHolder, int groupKey,
+ Dictionary dictionary) {
+ DistinctCountHLLAggregationFunction.DictIdsWrapper dictIdsWrapper =
groupByResultHolder.getResult(groupKey);
+ if (dictIdsWrapper == null) {
+ dictIdsWrapper = new
DistinctCountHLLAggregationFunction.DictIdsWrapper(dictionary);
+ groupByResultHolder.setValueForKey(groupKey, dictIdsWrapper);
+ }
+ return dictIdsWrapper._dictIdBitmap;
+ }
+
+ /**
+ * Helper method to set dictionary id for the given group keys into the
result holder.
+ */
+ private static void setDictIdForGroupKeys(GroupByResultHolder
groupByResultHolder, int[] groupKeys,
+ Dictionary dictionary, int dictId) {
+ for (int groupKey : groupKeys) {
+ getDictIdBitmap(groupByResultHolder, groupKey, dictionary).add(dictId);
+ }
+ }
+
+ private HyperLogLog convertToHLL(DictIdsWrapper dictIdsWrapper) {
+ Dictionary dictionary = dictIdsWrapper._dictionary;
+ RoaringBitmap dictIdBitmap = dictIdsWrapper._dictIdBitmap;
+ int numValues = dictIdBitmap.getCardinality();
+ PeekableIntIterator iterator = dictIdBitmap.getIntIterator();
+ HyperLogLog hyperLogLog = new HyperLogLog(_log2m);
+ while (iterator.hasNext()) {
+ hyperLogLog.offer(iterator.next());
+ }
Review comment:
Good to know. Could you share some articles explaining why?
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