sunchao commented on code in PR #58779:
URL: https://github.com/apache/spark/pull/58779#discussion_r4007571888
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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/nullExpressions.scala:
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@@ -187,8 +187,18 @@ private case class TypedNullLiteral(child: Expression)
override lazy val replacement: Expression = Literal.create(null,
child.dataType)
- override protected def withNewChildInternal(newChild: Expression):
TypedNullLiteral =
- copy(child = newChild)
+ override protected def withNewChildInternal(newChild: Expression):
Expression =
+ TypedNullLiteral.create(newChild)
+}
+
+private object TypedNullLiteral {
+ def create(child: Expression): Expression = {
+ if (child.resolved) {
+ Literal.create(null, child.dataType)
Review Comment:
[P2] Keep the null type synchronized through type coercion
`child.resolved` does not guarantee that its output type is final. With the
fixed-point analyzer and `spark.sql.function.concatBinaryAsString=true`,
`SELECT nullif(concat(X'61', X'62'), 'z')` constructs `NullIf` while the
all-binary `Concat` is already resolved as `BinaryType`. This branch therefore
becomes `Literal(null, BinaryType)`. `ConcatTypeCoercion` subsequently changes
the operand to `StringType`, but the literal cannot follow that change: ANSI
analysis casts the returned value back to binary, while non-ANSI analysis fails
with incompatible IF branch types. Previously the placeholder tracked the
changed child type. This affects both `spark.sql.alwaysInlineCommonExpr`
settings; the `With` path updates its references but cannot update this
detached literal. Please preserve type synchronization until coercion is
complete and add a regression across both ANSI and inline settings, checking
that this query still returns the string `ab`.
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