sunxiaoguang commented on code in PR #49453:
URL: https://github.com/apache/spark/pull/49453#discussion_r1915931322
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sql/core/src/main/scala/org/apache/spark/sql/jdbc/MySQLDialect.scala:
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@@ -112,6 +112,21 @@ private case class MySQLDialect() extends JdbcDialect with
SQLConfHelper with No
} else {
super.visitAggregateFunction(funcName, isDistinct, inputs)
}
+
+ override def visitCast(expr: String, exprDataType: DataType, dataType:
DataType): String = {
+ val databaseTypeDefinition = dataType match {
+ // MySQL uses CHAR in the cast function for the type LONGTEXT
+ case StringType => "CHAR"
+ // MySQL uses SIGNED INTEGER in the cast function for SMALLINT,
INTEGER and BIGINT.
+ // To avoid breaking code relying on ResultSet metadata, we support
BIGINT only at
+ // this time.
+ case LongType => "SIGNED INTEGER"
+ // MySQL uses BINARY in the cast function for the type BLOB
+ case BinaryType => "BINARY"
+ case _ =>
getJDBCType(dataType).map(_.databaseTypeDefinition).getOrElse(dataType.typeName)
Review Comment:
Sure, we can add an explicit error message for this case. But I'm not quite
familiar with Spark code base right now. I saw there are things like
_LEGACY_ERROR_TEMP_xxxx in code base. Could you please leave me some hints on
the rules to follow. Thanks.
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