slinkydeveloper commented on a change in pull request #18813:
URL: https://github.com/apache/flink/pull/18813#discussion_r810124695
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File path: docs/content/docs/dev/table/types.md
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@@ -1487,6 +1481,88 @@ Not supported.
{{< /tab >}}
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+Casting
+-------
+
+Flink SQL can perform casting between a defined pair `from` type and `target`
type. While some
+casting operations can always succeed no matter the input value, others can
fail at runtime, that
+is, for some input values there is no way to create a value for the target
type. For example, it's
+always possible to convert `INT` to `STRING`, but viceversa is not true, as
you can provide an
+input `STRING` which cannot be converted to `INT`, like `'abc'`.
+
+Flink SQL, during planning, rejects queries which cast pairs are invalid with
+a `ValidationException`, e.g. when trying to cast a `TIMESTAMP` to an
`INTERVAL`, but the user needs
+to handle manually cases where a cast pair is valid, but can fail at runtime.
Review comment:
> for invalid pairs-to-be-casted that throw a `ValidationException`
I changed this to:
> for invalid cast input and target type with a `ValidationException`
As it's flink that rejects the input and target types with a
`ValidationException`, and not the pair that itself rejects. Makes sense?
Also modified the next sentence. check it out
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