anilbash commented on a change in pull request #1859: [CALCITE-3863] Make
Truncate/Round return type inference overridable through rel data …
URL: https://github.com/apache/calcite/pull/1859#discussion_r397182094
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File path:
core/src/main/java/org/apache/calcite/rel/type/RelDataTypeSystem.java
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@@ -405,4 +405,103 @@ default RelDataType
deriveDecimalModType(RelDataTypeFactory typeFactory,
return null;
}
+ /**
+ * Infers the return type of a decimal truncate operation. Decimal truncate
+ * involves at least one decimal operand.
+ *
+ * <p>The default implementation is SQL:2003 compliant: the declared type of
+ * the result is the declared type of the first operand (decimal to be
truncated).
+ *
+ * @see Glossary#SQL2003 SQL:2003 Part 2 Section 6.27
+ *
+ * <p>Rules:
+ *
+ * <ul>
+ * <li>Let p1, s1 be the precision and scale of the first operand</li>
+ * <li>Let s2 be the scale value to truncate</li>
+ * <li>Let p, s be the precision and scale of the result</li>
+ * <li>Let d be the number of whole digits in the result</li>
+ * <li>Then the result type is a decimal with:
Review comment:
removed done.
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