Github user chenghao-intel commented on a diff in the pull request:

    https://github.com/apache/spark/pull/1586#discussion_r15504346
  
    --- Diff: 
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/stringOperations.scala
 ---
    @@ -209,6 +212,81 @@ case class EndsWith(left: Expression, right: 
Expression)
     }
     
     /**
    + * A function that returns the number of bytes in an expression
    + */
    +case class Length(child: Expression) extends UnaryExpression {
    +
    +  type EvaluatedType = Any
    +
    +  override def dataType = IntegerType
    +
    +  override def foldable = child.foldable
    +
    +  override def nullable = child.nullable
    +
    +  override def toString = s"Length($child)"
    +
    +  override def eval(input: Row): EvaluatedType = {
    +    val string = child.eval(input)
    +    if (string == null) {
    +      null
    +    } else if (!string.isInstanceOf[String]) {
    +      string.toString.length
    +    } else {
    +      string.toString.getBytes.length
    +    }
    +  }
    +
    +}
    +
    +object StrlenConstants {
    +  val DefaultEncoding = "ISO-8859-1"
    +}
    +
    +/**
    + * A function that returns the number of characters in a string expression
    + */
    +case class Strlen(child: Expression, encoding : Expression) extends 
UnaryExpression
    +  with Logging {
    +
    +  type EvaluatedType = Any
    +
    +  override def dataType = IntegerType
    +
    +  override def foldable = child.foldable
    +
    +  override def nullable = child.nullable
    +
    +  override def toString = s"Strlen($child, $encoding)"
    +
    +  override def eval(input: Row): EvaluatedType = {
    +    val string = child.eval(input)
    +    if (string == null) {
    +      null
    +    } else if (!string.isInstanceOf[String]) {
    +      throw new IllegalArgumentException(s"Non-string value [$string] 
provided to strlen")
    --- End diff --
    
    @javadba I think you probably also need to update rules in the 
`HiveTypeCoercion`, which will insert the expression `Cast` if the child 
expression type are not satisfied, and then you won't need the children data 
type checking here.


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