maropu commented on a change in pull request #28106: [SPARK-31335][SQL] Add try
function support
URL: https://github.com/apache/spark/pull/28106#discussion_r407342553
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/misc.scala
##########
@@ -198,3 +201,69 @@ case class TypeOf(child: Expression) extends
UnaryExpression {
defineCodeGen(ctx, ev, _ =>
s"""UTF8String.fromString(${child.dataType.catalogString})""")
}
}
+
+// scalastyle:off line.size.limit
+@ExpressionDescription(
+ usage = """
+ _FUNC_(expr) - Evaluate an expression and handle certain types of
execution errors by returning NULL.
+ In cases where it is preferable that queries produce NULL instead of
failing when corrupt or invalid data is encountered, the TRY function may be
useful, especially when ANSI mode is on and the users need null-tolerant on
certain columns or outputs.
+ AnalysisExceptions will not be handled by this, typically errors handled
by TRY function are:
+
+ * Division by zero,
+ * Invalid casting,
+ * Numeric value out of range,
+ * e.t.c
+ """,
+ examples = """
+ Examples:
+ > SELECT _FUNC_(1 / 0);
+ NULL
+ """,
+ since = "3.1.0")
+// scalastyle:on line.size.limit
+case class TryExpression(child: Expression) extends UnaryExpression {
+
+ override def nullable: Boolean = true
+ override def dataType: DataType = child.dataType
+ override def prettyName: String = "try"
+
+ override def eval(input: InternalRow): Any = {
+ try {
+ child.eval(input)
+ } catch {
+ case e if TryExpression.canSuppress(e) => null
+ }
+ }
+
+ override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
+ val eval = child.genCode(ctx)
+ val javaType = CodeGenerator.javaType(dataType)
+ ev.copy(code =
+ code"""
+ boolean ${ev.isNull} = false;
+ $javaType ${ev.value} = ${CodeGenerator.defaultValue(dataType)};
+ try {
+ ${eval.code}
+ ${ev.isNull} = ${eval.isNull};
+ ${ev.value} = ${eval.value};
+ } catch (java.lang.Exception e) {
+ if
(org.apache.spark.sql.catalyst.expressions.TryExpression.canSuppress(e)) {
+ ${ev.isNull} = true;
+ } else {
+ throw e;
+ }
+ }""")
+ }
+}
+
+object TryExpression {
+
+ def canSuppress(e: Throwable): Boolean = e match {
+ case _: IllegalArgumentException |
+ _: ArithmeticException |
+ _: DateTimeException |
+ _: NumberFormatException |
+ _: UnsupportedEncodingException => true
Review comment:
Ah, I see. Could you leave some comments here about the non-handled cases?
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