huaxingao commented on a change in pull request #29324:
URL: https://github.com/apache/spark/pull/29324#discussion_r463926557
##########
File path: sql/core/src/main/scala/org/apache/spark/sql/jdbc/JdbcDialects.scala
##########
@@ -184,15 +189,56 @@ abstract class JdbcDialect extends Serializable {
/**
* Rename an existing table.
*
- * TODO (SPARK-32382): Override this method in the dialects that don't
support such syntax.
- *
* @param oldTable The existing table.
* @param newTable New name of the table.
* @return The SQL statement to use for renaming the table.
*/
def renameTable(oldTable: String, newTable: String): String = {
s"ALTER TABLE $oldTable RENAME TO $newTable"
}
+
+ /**
+ * Alter an existing table.
+ *
+ * @param tableName The name of the table to be altered.
+ * @param changes Changes to apply to the table.
+ * @return The SQL statement to use for altering the table.
+ */
+ def alterTable(tableName: String, changes: Seq[TableChange]): Array[String]
= {
+ val updateClause = mutable.ArrayBuilder.make[String]
+ for (change <- changes) {
+ change match {
+ case add: AddColumn =>
+ add.fieldNames match {
+ case Array(name) =>
+ val dataType = JdbcUtils.getJdbcType(add.dataType(),
this).databaseTypeDefinition
+ updateClause += s"ALTER TABLE $tableName ADD COLUMN $name
$dataType"
+ case _ =>
+ throw new IllegalArgumentException(s"Unsupported TableChange
fieldNames" +
+ s" ${add.fieldNames}")
Review comment:
fieldNames with 2 elements is not supported. It is for nested columns,
e.g.
```
val pointStruct = new StructType().add("x", DoubleType).add("y", DoubleType)
val tableSchema = schema.add("point", pointStruct)
TableChange.addColumn(Array("point", "z"), DoubleType))
```
I don't think add nested column is supported by any of these commonly used
databases (Oracle, DB2, MS SQL Server, Postgres, etc)
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
[email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
