[GitHub] [incubator-pinot] atris commented on a change in pull request #7141: Support Dictionary Based Plan For DISTINCT

[GitBox <gi...@apache.org>]

atris commented on a change in pull request #7141:
URL: https://github.com/apache/incubator-pinot/pull/7141#discussion_r666455606



##########
File path: pinot-core/src/main/java/org/apache/pinot/core/plan/maker/InstancePlanMakerImplV2.java
##########
@@ -264,4 +267,31 @@ static boolean isFitForDictionaryBasedPlan(QueryContext queryContext, IndexSegme
     }
     return true;
   }
+
+  /**
+   * Returns dictionary based distinct plan node iff supported, else distinct plan node
+   */
+  private PlanNode getDistinctExecutionNode(IndexSegment indexSegment, QueryContext queryContext) {
+    AggregationFunction[] aggregationFunctions = queryContext.getAggregationFunctions();
+
+    // If we have gotten here, it must have been verified that there is only on aggregation function in the context
+    // and it is a DistinctAggregationFunction
+
+    DistinctAggregationFunction distinctAggregationFunction = (DistinctAggregationFunction) aggregationFunctions[0];
+    List<ExpressionContext> expressions = distinctAggregationFunction.getInputExpressions();
+
+    if (expressions.size() == 1 && queryContext.getFilter() == null) {
+      ExpressionContext expression = expressions.get(0);
+
+      if (expression.getType() == ExpressionContext.Type.IDENTIFIER) {
+        String column = expression.getIdentifier();
+        Dictionary dictionary = indexSegment.getDataSource(column).getDictionary();
+        if (dictionary != null && dictionary.isSorted()) {

Review comment:
       How would we apply limits on it?




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