[GitHub] [spark] ScrapCodes commented on a change in pull request #30025: [SPARK-33095][SQL] Support ALTER TABLE in JDBC v2 Table Catalog: add, update type and nullability of columns (MySQL dialect)

[GitBox <gi...@apache.org>]

ScrapCodes commented on a change in pull request #30025:
URL: https://github.com/apache/spark/pull/30025#discussion_r506320770



##########
File path: sql/core/src/main/scala/org/apache/spark/sql/jdbc/MySQLDialect.scala
##########
@@ -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:
       Are you ok with the change in the APIs e.g. https://github.com/apache/spark/blob/1aa184763aa49d70907669b2d8af5a713ee0d7fa/sql/catalyst/src/main/java/org/apache/spark/sql/connector/catalog/TableChange.java#L157.0 
   
   Or you are suggesting something else?
   
   I can try to do it, which ever way it is.  
   
   




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