huaxingao commented on a change in pull request #29324:
URL: https://github.com/apache/spark/pull/29324#discussion_r465203303
##########
File path: sql/core/src/main/scala/org/apache/spark/sql/jdbc/JdbcDialects.scala
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@@ -184,15 +189,62 @@ 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.
+ * TODO (SPARK-32523): Override this method in the dialects that have
different syntax.
+ *
+ * @param tableName The name of the table to be altered.
+ * @param changes Changes to apply to the table.
+ * @return The SQL statements to use for altering the table.
+ */
+ def alterTable(tableName: String, changes: Seq[TableChange]): Array[String]
= {
+ val updateClause = ArrayBuilder.make[String]
+ for (change <- changes) {
+ change match {
+ case add: AddColumn =>
+ add.fieldNames match {
+ case Array(name) =>
Review comment:
@cloud-fan I changed code to what you suggested.
We don't support nested column in JDBC yet. In `JdbcUtils.getCatalystType`,
we map `java.sql.Types.STRUCT => StringType`. In `getCommonJDBCType`, we
don't have a match case for StructType and the default is None. Seems to me
currently it is not possible to reach the code path of multiple parts
fieldNames in `JdbcDialects.alterTable`, so I will not have a negative test
case for this code path for now.
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