huaxingao commented on a change in pull request #30142:
URL: https://github.com/apache/spark/pull/30142#discussion_r513616044
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File path: sql/core/src/main/scala/org/apache/spark/sql/jdbc/MySQLDialect.scala
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@@ -57,6 +58,25 @@ private case object MySQLDialect extends JdbcDialect {
s"ALTER TABLE $tableName MODIFY COLUMN ${quoteIdentifier(columnName)}
$newDataType"
}
+ // See Old Syntax: https://dev.mysql.com/doc/refman/5.6/en/alter-table.html
+ // According to https://dev.mysql.com/worklog/task/?id=10761 old syntax
works for
+ // both versions of MySQL i.e. 5.x and 8.0
+ // The old syntax requires us to have type definition. Since we do not have
type
+ // information, we throw the exception.
+ override def getRenameColumnQuery(
+ tableName: String,
+ columnName: String,
+ newName: String): String = {
+ if (SQLConf.get.jdbcMySQLVersion.matches("^8\\.[0-9].*")) {
Review comment:
Instead of using a session config, we probably want to get database
version using `DatabaseMetaData` in `JdbcUtils.altertable` and pass the info
here, and only do `RENAME` if version >= 8
```
conn.getMetaData.getDatabaseMajorVersion
```
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