liyafan82 commented on a change in pull request #2330:
URL: https://github.com/apache/calcite/pull/2330#discussion_r561508574
##########
File path: core/src/test/java/org/apache/calcite/rex/RexProgramTest.java
##########
@@ -2857,6 +2857,108 @@ private void checkSarg(String message, Sarg sarg,
is(2), is("Sarg[[3..8], [10..20]]"));
}
+ /** Tests {@link Sarg#numDistinctVals(RelDataType)}. */
+ @Test void testSargNdv() {
+ RelDataType nonNullableInt =
typeFactory.createSqlType(SqlTypeName.INTEGER);
+ RelDataType nullableInt =
typeFactory.createTypeWithNullability(nonNullableInt, true);
+
+ RelDataType nonNullableFloat =
typeFactory.createSqlType(SqlTypeName.FLOAT);
+ RelDataType nullableFloat =
typeFactory.createTypeWithNullability(nonNullableFloat, true);
+
+ // point: 10 (non-nullable)
+ Sarg sarg = Sarg.of(false,
+ ImmutableRangeSet.of(Range.closed(10, 10)));
+ assertThat(sarg.numDistinctVals(nonNullableInt), is(1.0));
Review comment:
Thank you for the good suggestion.
I have revised the code accordingly.
##########
File path: core/src/main/java/org/apache/calcite/util/RangeSets.java
##########
@@ -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:
Nice catch. Thank you.
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