rubenada commented on code in PR #6477:
URL: https://github.com/apache/hive/pull/6477#discussion_r3250704963


##########
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/stats/FilterSelectivityEstimator.java:
##########
@@ -603,6 +605,151 @@ private Optional<Float> extractLiteral(SqlTypeName 
typeName, Object boundValueOb
     return Optional.of(value);
   }
 
+  private double computeSearchSelectivity(RexCall search) {
+    return new SearchSelectivityHelper<>(search).compute();
+  }
+
+  /**
+   * Similar to {@link SearchTransformer}, but computing the selectivity of 
the expression.
+   */
+  private final class SearchSelectivityHelper<C extends Comparable<C>> {
+    private final RexNode ref;
+    private final Sarg<C> sarg;
+    private final RelDataType operandType;
+
+    private SearchSelectivityHelper(RexCall search) {
+      ref = search.getOperands().get(0);
+      RexLiteral literal = (RexLiteral) search.operands.get(1);
+      sarg = Objects.requireNonNull(literal.getValueAs(Sarg.class), "Sarg");
+      operandType = literal.getType();
+    }
+
+    private RexNode makeLiteral(C value) {
+      return rexBuilder.makeLiteral(value, operandType, true, true);
+    }
+
+    private double compute() {
+      final List<Double> selectivityList = new ArrayList<>();
+      final List<RexNode> inLiterals = new ArrayList<>();
+
+      if (sarg.nullAs == RexUnknownAs.TRUE) {
+        selectivityList.add(
+            rexBuilder.makeCall(SqlStdOperatorTable.IS_NULL, 
ref).accept(FilterSelectivityEstimator.this));
+      }
+
+      RangeSets.forEach(sarg.rangeSet, new RangeSets.Consumer<C>() {
+        @Override
+        public void all() {
+          selectivityList.add(1.0);
+        }
+
+        @Override
+        public void singleton(C value) {
+          inLiterals.add(rexBuilder.makeLiteral(value, operandType, true, 
true));
+        }
+
+        @Override
+        public void atLeast(C lower) {
+          Optional<Float> lowerLiteral = extractLiteral(makeLiteral(lower));
+          if (lowerLiteral.isEmpty()) {
+            selectivityList.add(DEFAULT_COMPARISON_SELECTIVITY);
+          } else {
+            processRange(() -> DEFAULT_COMPARISON_SELECTIVITY,
+                Range.range(lowerLiteral.get(), BoundType.CLOSED, 
Float.POSITIVE_INFINITY, BoundType.CLOSED));
+          }
+        }
+
+        @Override
+        public void atMost(C upper) {
+          Optional<Float> upperLiteral = extractLiteral(makeLiteral(upper));
+          if (upperLiteral.isEmpty()) {
+            selectivityList.add(DEFAULT_COMPARISON_SELECTIVITY);
+          } else {
+            processRange(() -> DEFAULT_COMPARISON_SELECTIVITY,
+                Range.range(Float.NEGATIVE_INFINITY, BoundType.CLOSED, 
upperLiteral.get(), BoundType.CLOSED));
+          }
+        }
+
+        @Override
+        public void greaterThan(C lower) {
+          Optional<Float> lowerLiteral = extractLiteral(makeLiteral(lower));
+          if (lowerLiteral.isEmpty()) {
+            selectivityList.add(DEFAULT_COMPARISON_SELECTIVITY);
+          } else {
+            processRange(() -> DEFAULT_COMPARISON_SELECTIVITY,
+                Range.range(lowerLiteral.get(), BoundType.OPEN, 
Float.POSITIVE_INFINITY, BoundType.CLOSED));
+          }
+        }
+
+        @Override
+        public void lessThan(C upper) {
+          Optional<Float> upperLiteral = extractLiteral(makeLiteral(upper));
+          if (upperLiteral.isEmpty()) {
+            selectivityList.add(DEFAULT_COMPARISON_SELECTIVITY);
+          } else {
+            processRange(() -> DEFAULT_COMPARISON_SELECTIVITY,
+                Range.range(Float.NEGATIVE_INFINITY, BoundType.CLOSED, 
upperLiteral.get(), BoundType.OPEN));
+          }
+        }
+
+        @Override
+        public void closed(C lower, C upper) {
+          processRange(lower, BoundType.CLOSED, upper, BoundType.CLOSED);
+        }
+
+        @Override
+        public void closedOpen(C lower, C upper) {
+          processRange(lower, BoundType.CLOSED, upper, BoundType.OPEN);
+        }
+
+        @Override
+        public void openClosed(C lower, C upper) {
+          processRange(lower, BoundType.OPEN, upper, BoundType.CLOSED);
+        }
+
+        @Override
+        public void open(C lower, C upper) {
+          processRange(lower, BoundType.OPEN, upper, BoundType.OPEN);
+        }
+
+        private void processRange(C lower, BoundType lowerBoundType, C upper, 
BoundType upperBoundType) {
+          RexNode lowerRexLiteral = makeLiteral(lower);
+          RexNode upperRexLiteral = makeLiteral(upper);
+          Supplier<Double> defaultSelectivity =
+              () -> computeFunctionSelectivity(List.of(ref, lowerRexLiteral, 
upperRexLiteral));
+          Optional<Float> lowerLiteral = extractLiteral(lowerRexLiteral);
+          Optional<Float> upperLiteral = extractLiteral(upperRexLiteral);
+          if (lowerLiteral.isEmpty() || upperLiteral.isEmpty()) {
+            selectivityList.add(defaultSelectivity.get());
+          } else {
+            processRange(defaultSelectivity,
+                Range.range(lowerLiteral.get(), lowerBoundType, 
upperLiteral.get(), upperBoundType));
+          }
+        }
+
+        private void processRange(Supplier<Double> defaultSelectivity, 
Range<Float> boundaries) {
+          
selectivityList.add(computeRangePredicateSelectivity(defaultSelectivity, ref, 
boundaries));
+        }
+      });
+
+      switch (inLiterals.size()) {
+      case 0:
+        break;
+      case 1:
+        selectivityList.add(rexBuilder.makeCall(SqlStdOperatorTable.EQUALS, 
ref, inLiterals.get(0))
+            .accept(FilterSelectivityEstimator.this));
+        break;
+      default:
+        List<RexNode> operands = new ArrayList<>(inLiterals.size() + 1);
+        operands.add(ref);
+        operands.addAll(inLiterals);
+        selectivityList.add(rexBuilder.makeCall(HiveIn.INSTANCE, 
operands).accept(FilterSelectivityEstimator.this));
+      }
+
+      return selectivityList.size() == 1 ? selectivityList.get(0) : 
computeDisjunctionSelectivity(selectivityList);

Review Comment:
   Indeed. I have applied the change to add the ranges selectivities (and it 
gives better results in certain tests, as expected).
   I have kept the "disjunction logic" for the combination with the other 
expressions (EQ/IN, IS_NULL), since it seems more aligned with how this class 
works in general when computing OR-combined RexNodes. But I agree this can be 
revisits in the future.



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