imback82 commented on a change in pull request #27444: [SPARK-30614][SQL] The
native ALTER COLUMN syntax should change one property at a time
URL: https://github.com/apache/spark/pull/27444#discussion_r374361369
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
##########
@@ -2940,30 +2940,61 @@ class AstBuilder(conf: SQLConf) extends
SqlBaseBaseVisitor[AnyRef] with Logging
}
/**
- * Parse a [[AlterTableAlterColumnStatement]] command.
+ * Parse a [[AlterTableAlterColumnStatement]] command to change column type
*
* For example:
* {{{
* ALTER TABLE table1 ALTER COLUMN a.b.c TYPE bigint
- * ALTER TABLE table1 ALTER COLUMN a.b.c TYPE bigint COMMENT 'new comment'
+ * }}}
+ */
+ override def visitAlterTableColumnType(
+ ctx: AlterTableColumnTypeContext): LogicalPlan = withOrigin(ctx) {
+ AlterTableAlterColumnStatement(
+ visitMultipartIdentifier(ctx.table),
+ typedVisit[Seq[String]](ctx.column),
+ dataType = Some(typedVisit[DataType](ctx.dataType)),
+ nullable = None,
+ comment = None,
+ position = None)
+ }
+
+ /**
+ * Parse a [[AlterTableAlterColumnStatement]] command to change column
comment
+ *
+ * For example:
+ * {{{
* ALTER TABLE table1 ALTER COLUMN a.b.c COMMENT 'new comment'
* }}}
*/
- override def visitAlterTableColumn(
- ctx: AlterTableColumnContext): LogicalPlan = withOrigin(ctx) {
- val verb = if (ctx.CHANGE != null) "CHANGE" else "ALTER"
- if (ctx.dataType == null && ctx.commentSpec() == null && ctx.colPosition
== null) {
- operationNotAllowed(
- s"ALTER TABLE table $verb COLUMN requires a TYPE or a COMMENT or a
FIRST/AFTER", ctx)
- }
+ override def visitAlterTableColumnComment(
+ ctx: AlterTableColumnCommentContext): LogicalPlan = withOrigin(ctx) {
+ AlterTableAlterColumnStatement(
+ visitMultipartIdentifier(ctx.table),
+ typedVisit[Seq[String]](ctx.column),
+ dataType = None,
+ nullable = None,
+ comment = Some(visitCommentSpec(ctx.commentSpec())),
+ position = None)
+ }
+ /**
+ * Parse a [[AlterTableAlterColumnStatement]] command to change column
position
+ *
+ * For example:
+ * {{{
+ * ALTER TABLE table1 ALTER COLUMN a.b.c FIRST
+ * ALTER TABLE table1 ALTER COLUMN a.b.c AFTER x
+ * }}}
+ */
+ override def visitAlterTableColumnPosition(
+ ctx: AlterTableColumnPositionContext): LogicalPlan = withOrigin(ctx) {
AlterTableAlterColumnStatement(
visitMultipartIdentifier(ctx.table),
typedVisit[Seq[String]](ctx.column),
- dataType = Option(ctx.dataType).map(typedVisit[DataType]),
+ dataType = None,
nullable = None,
- comment = Option(ctx.commentSpec()).map(visitCommentSpec),
- position = Option(ctx.colPosition).map(typedVisit[ColumnPosition]))
+ comment = None,
+ position = Some(typedVisit[ColumnPosition](ctx.colPosition)))
}
Review comment:
I could also update `AlterTAbleAlterColumnStatement` to be like:
```Scala
case class AlterTableAlterColumnStatement(
tableName: Seq[String],
column: Seq[String],
dataType: Option[DataType],
nullable: Option[Boolean],
comment: Option[String],
position: Option[ColumnPosition],
isHive: Boolean) extends ParsedStatement {
require(
isHive || Seq(dataType, nullable, comment,
position).filter(_.nonEmpty).length == 1,
"Only one property can be changed at a time.")
}
```
to be safe, but I didn't add it because of `isHive` hack.
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