dongjoon-hyun commented on a change in pull request #27965: [SPARK-31205][SQL]
support string literal as the second argument of date_add/date_sub functions
URL: https://github.com/apache/spark/pull/27965#discussion_r395790680
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TypeCoercion.scala
##########
@@ -1043,6 +1045,34 @@ object TypeCoercion {
}
}
}
+
+ /**
+ * A special rule to support string literal as the second argument of
date_add/date_sub functions,
+ * to keep backward compatibility as a temporary workaround.
+ * TODO(SPARK-28589): implement ANSI type type coercion and handle string
literals.
+ */
+ object StringLiteralCoercion extends TypeCoercionRule {
Review comment:
This causes a behavior difference in arithmatic operations, too. Could you
describe the following change in the PR description?
**2.4.5 and 3.0.0-preview2**
```
scala> sql("select (cast('2020-03-28' AS DATE) + '1')").show
org.apache.spark.sql.AnalysisException: cannot resolve '(CAST('2020-03-28'
AS DATE) + CAST('1' AS DOUBLE))' due to data type mismatch: differing types in
'(CAST('2020-03-28' AS DATE) + CAST('1' AS DOUBLE))' (date and double).; line 1
pos 8;
```
This PR.
```
scala> sql("select (cast('2020-03-28' AS DATE) + '1')").show
+-------------------------------------+
|date_add(CAST(2020-03-28 AS DATE), 1)|
+-------------------------------------+
| 2020-03-29|
+-------------------------------------+
```
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