Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/14874#discussion_r76842003
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/command/views.scala ---
@@ -202,3 +196,67 @@ case class CreateViewCommand(
)
}
}
+
+/**
+ * Alter a view with given query plan. If the view name contains database
prefix, this command will
+ * alter a permanent view matching the given name, or throw an exception
if view not exist. Else,
+ * this command will try to alter a temporary view first, if view not
exist, try permanent view
+ * next, if still not exist, throw an exception.
+ *
+ * @param name the name of this view.
+ * @param originalText the original SQL text of this view. Note that we
can only alter a view by
+ * SQL API, which means we always have originalText.
+ * @param query the logical plan that represents the view; this is used to
generate a canonicalized
+ * version of the SQL that can be saved in the catalog.
+ */
+case class AlterViewCommand(
+ name: TableIdentifier,
+ originalText: String,
+ query: LogicalPlan) extends RunnableCommand {
+
+ override protected def innerChildren: Seq[QueryPlan[_]] = Seq(query)
+
+ override def run(session: SparkSession): Seq[Row] = {
+ // If the plan cannot be analyzed, throw an exception and don't
proceed.
+ val qe = session.sessionState.executePlan(query)
+ qe.assertAnalyzed()
+ val analyzedPlan = qe.analyzed
+
+ val tableMeta = session.sessionState.catalog.getTableMetadata(name)
+ if (tableMeta.tableType != CatalogTableType.VIEW) {
+ throw new AnalysisException(s"${tableMeta.identifier} is not a
view.")
+ }
+
+ if (name.database.isDefined) {
+ alterPermanentView(session, analyzedPlan)
+ } else if (session.sessionState.catalog.isTemporaryTable(name)) {
+ session.sessionState.catalog.createTempView(name.table,
analyzedPlan, overrideIfExists = true)
+ } else {
+ alterPermanentView(session, analyzedPlan)
+ }
+
+ Seq.empty[Row]
+ }
+
+ private def alterPermanentView(session: SparkSession, analyzedPlan:
LogicalPlan): Unit = {
+ val viewSQL: String = new SQLBuilder(analyzedPlan).toSQL
+ // Validate the view SQL - make sure we can parse it and analyze it.
+ // If we cannot analyze the generated query, there is probably a bug
in SQL generation.
+ try {
+ session.sql(viewSQL).queryExecution.assertAnalyzed()
+ } catch {
+ case NonFatal(e) =>
+ throw new RuntimeException(s"Failed to analyze the canonicalized
SQL: $viewSQL", e)
+ }
+
+ val viewTableMeta = CatalogTable(
+ identifier = name,
+ tableType = CatalogTableType.VIEW,
+ storage = CatalogStorageFormat.empty,
+ schema = analyzedPlan.schema,
+ viewOriginalText = Some(originalText),
+ viewText = Some(viewSQL))
--- End diff --
Since we are doing the alter view, we should not lose the existing fields,
e.g., comment and table properties.
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