[SPARK-23774][SQL] Cast to CHAR/VARCHAR should truncate the values

apache · May 21, 2018 · f19cda3 · f19cda3
1 parent a33dcf4
commit f19cda3
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Showing 2 changed files with 49 additions and 1 deletion.
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
@@ -1173,7 +1173,18 @@ class AstBuilder(conf: SQLConf) extends SqlBaseBaseVisitor[AnyRef] with Logging
    * Create a [[Cast]] expression.
    */
   override def visitCast(ctx: CastContext): Expression = withOrigin(ctx) {
-    Cast(expression(ctx.expression), visitSparkDataType(ctx.dataType))
+    typedVisit[DataType](ctx.dataType) match {
+      case t: CharType =>
+        validate(t.length > 0, s"Char length ${t.length} is out of range [1, 255]", ctx)
+        Substring(Cast(expression(ctx.expression), visitSparkDataType(ctx.dataType)),
+          Literal(1), Literal(t.length))
+      case t: VarcharType =>
+        validate(t.length > 0, s"VarChar length ${t.length} is out of range [1, 65535]", ctx)
+        Substring(Cast(expression(ctx.expression), visitSparkDataType(ctx.dataType)),
+          Literal(1), Literal(t.length))
+      case _ =>
+        Cast(expression(ctx.expression), visitSparkDataType(ctx.dataType))
+    }
   }
 
   /**

diff --git a/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
@@ -24,6 +24,7 @@ import java.util.concurrent.atomic.AtomicBoolean
 
 import org.apache.spark.{AccumulatorSuite, SparkException}
 import org.apache.spark.scheduler.{SparkListener, SparkListenerJobStart}
+import org.apache.spark.sql.catalyst.parser.ParseException
 import org.apache.spark.sql.catalyst.util.StringUtils
 import org.apache.spark.sql.execution.aggregate
 import org.apache.spark.sql.execution.aggregate.{HashAggregateExec, SortAggregateExec}
@@ -2792,4 +2793,40 @@ class SQLQuerySuite extends QueryTest with SharedSQLContext {
       }
     }
   }
+
+  test("`Cast` to CHAR/VARCHAR should truncate the values") {
+    withTable("t") {
+      val m = intercept[ParseException] {
+        sql("SELECT CAST('abc' AS CHAR(0))")
+      }.getMessage
+      assert(m.contains("Char length 0 is out of range [1, 255]"))
+
+      val m2 = intercept[ParseException] {
+        sql("SELECT CAST('abc' AS VARCHAR(0))")
+      }.getMessage
+      assert(m2.contains("VarChar length 0 is out of range [1, 65535]"))
+
+      checkAnswer(
+        sql("SELECT CAST('abc' AS CHAR(2)), CAST('abc' AS CHAR(4))"),
+        Row("ab", "abc"))
+
+      sql("CREATE TABLE t(a STRING) USING PARQUET")
+      sql("INSERT INTO t VALUES ('abc')")
+      sql("INSERT INTO t VALUES (null)")
+
+      checkAnswer(
+        sql("SELECT CAST(a AS CHAR(2)), CAST(a AS CHAR(3)), CAST(a AS CHAR(4)) FROM t"),
+        Row("ab", "abc", "abc") :: Row(null, null, null) :: Nil)
+
+      sql(
+        """
+          |CREATE TABLE t_ctas
+          |USING ORC
+          |AS SELECT CAST(a AS CHAR(2)) c1, CAST(a AS CHAR(3)) c2, CAST(a AS CHAR(4)) c3 FROM t
+        """.stripMargin)
+      checkAnswer(
+        sql("SELECT * FROM t_ctas"),
+        Row("ab", "abc", "abc") :: Row(null, null, null) :: Nil)
+    }
+  }
 }