[GitHub] [spark] cloud-fan commented on a change in pull request #31474: [SPARK-34359][SQL] add a legacy config to restore the output schema of SHOW DATABASES

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

cloud-fan commented on a change in pull request #31474:
URL: https://github.com/apache/spark/pull/31474#discussion_r570267617



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File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/v2Commands.scala
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@@ -325,11 +325,13 @@ case class AlterNamespaceSetLocation(
  */
 case class ShowNamespaces(
     namespace: LogicalPlan,
-    pattern: Option[String]) extends Command {
+    pattern: Option[String],
+    override val output: Seq[Attribute] = ShowNamespaces.OUTPUT) extends Command {

Review comment:
       I think it's better to put the `output` field in the constructor so that it's more stable (copying the node will not regenerate the output attributes). It also helps if we want to support self-join later.




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