vlsi commented on a change in pull request #2330:
URL: https://github.com/apache/calcite/pull/2330#discussion_r560953566
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File path: core/src/main/java/org/apache/calcite/util/RangeSets.java
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@@ -105,6 +110,45 @@ private RangeSets() {}
return 0;
}
+ /**
+ * Estimates the number of distinct values for a range (if possible).
+ * A null is returned if the number of distinct values is infinity or
unknown.
+ */
+ public static <C extends Comparable<C>> @Nullable Double numDistinctVals(
+ Range<C> range, RelDataType type) {
+ if (RangeSets.isPoint(range)) {
+ return 1.0;
+ }
+ if (!range.hasLowerBound() || !range.hasUpperBound()) {
+ // infinity range.
+ return null;
+ }
+ C lower = range.lowerEndpoint();
+ C upper = range.upperEndpoint();
+
+ if (lower instanceof Number && upper instanceof Number) {
+ Number lowerNum = (Number) lower;
+ Number upperNum = (Number) upper;
+
+ boolean discreteType = type.getSqlTypeName() ==
SqlTypeName.BOOLEAN.BOOLEAN
Review comment:
Is `.BOOLEAN.BOOLEAN` expected here?
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