xiarixiaoyao commented on code in PR #8380:
URL: https://github.com/apache/hudi/pull/8380#discussion_r1166535195
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hudi-common/src/main/java/org/apache/hudi/avro/HoodieAvroUtils.java:
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@@ -1040,6 +1035,32 @@ private static Object
rewritePrimaryTypeWithDiffSchemaType(Object oldValue, Sche
throw new AvroRuntimeException(String.format("cannot support rewrite value
for schema type: %s since the old schema type is: %s", newSchema, oldSchema));
}
+ /**
+ * When there is a lost in scale, rounding is required to be performed when
performing casts.
+ * For types that have a fix scale, the results of the cast will need to be
the same for COW and MOR.
+ * <p>
+ * NOTE: COW uses Spark's default rounding of HALF_UP (if Spark entry points
are used).
+ * <p>
+ * Floating point types are not considered here as they are susceptible to
floating point rounding errors.
+ * <p>
+ * Summary:
+ * <ul>
+ * <li>double/string -> decimal: HALF_UP</li>
+ * <li>float -> decimal: HALF_EVEN</li>
+ * </ul>
Review Comment:
spark always use HALF_UP to cast FractionalType（float/double） to DecimalType
why we use HAL_EVEN to cast float -> decimal
BTW hive/presto also use HALF_UP
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