cloud-fan commented on a change in pull request #30025:
URL: https://github.com/apache/spark/pull/30025#discussion_r506106800
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File path: sql/core/src/main/scala/org/apache/spark/sql/jdbc/MySQLDialect.scala
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@@ -48,4 +48,26 @@ private case object MySQLDialect extends JdbcDialect {
}
override def isCascadingTruncateTable(): Option[Boolean] = Some(false)
+
+ // See https://dev.mysql.com/doc/refman/8.0/en/alter-table.html
+ override def getUpdateColumnTypeQuery(
+ tableName: String,
+ columnName: String,
+ newDataType: String): String = {
+ s"ALTER TABLE $tableName MODIFY COLUMN ${quoteIdentifier(columnName)}
$newDataType"
+ }
+
+ // See https://dev.mysql.com/doc/refman/8.0/en/alter-table.html
+ // require to have column data type to change the column nullability
+ // ALTER TABLE tbl_name MODIFY [COLUMN] col_name column_definition
+ // column_definition:
+ // data_type [NOT NULL | NULL]
+ // e.g. ALTER TABLE t1 MODIFY b INT NOT NULL;
Review comment:
Spark knows the table schema and data type info is available. We need to
pass the column type info to here though.
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