Github user 10110346 commented on a diff in the pull request:
https://github.com/apache/spark/pull/18228#discussion_r126359992
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringExpressions.scala
---
@@ -1199,6 +1199,82 @@ case class Substring(str: Expression, pos:
Expression, len: Expression)
}
/**
+ * Returns the rightmost n characters from the string.
+ */
+@ExpressionDescription(
+ usage = "_FUNC_(str, len) - Returns the rightmost `len` characters from
the string `str`.",
+ extended = """
+ Examples:
+ > SELECT _FUNC_('Spark SQL', 3);
+ SQL
+ """)
+case class Right(str: Expression, len: Expression)
+ extends BinaryExpression with ImplicitCastInputTypes with NullIntolerant
{
--- End diff --
`Left` has been implemented by substring, but `Right` implemented by
substring may be not very good.
case class Right(str: Expression, len: Expression, child: Expression)
extends RuntimeReplaceable {
def this(str: Expression, len: Expression) = {
this(str, len, Substring(str, If(LessThanOrEqual(len, Literal(0)),
Literal(Integer.MAX_VALUE), UnaryMinus(len)), len))
}
override def flatArguments: Iterator[Any] = Iterator(str, len)
override def sql: String = s"$prettyName(${str.sql}, ${len.sql})"
}
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