Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/14897#discussion_r80985641
--- Diff: sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala ---
@@ -2433,31 +2433,65 @@ class Dataset[T] private[sql](
}
/**
- * Creates a temporary view using the given name. The lifetime of this
+ * Creates a local temporary view using the given name. The lifetime of
this
* temporary view is tied to the [[SparkSession]] that was used to
create this Dataset.
*
+ * Local temporary view is session-scoped. Its lifetime is the lifetime
of the session that
+ * created it, i.e. it will be automatically dropped when the session
terminates. It's not
+ * tied to any databases, i.e. we can't use `db1.view1` to reference a
local temporary view.
+ *
* @throws AnalysisException if the view name already exists
*
* @group basic
* @since 2.0.0
*/
@throws[AnalysisException]
def createTempView(viewName: String): Unit = withPlan {
- createViewCommand(viewName, replace = false)
+ createTempViewCommand(viewName, replace = false, global = false)
}
+
+
/**
- * Creates a temporary view using the given name. The lifetime of this
+ * Creates a local temporary view using the given name. The lifetime of
this
* temporary view is tied to the [[SparkSession]] that was used to
create this Dataset.
*
* @group basic
* @since 2.0.0
*/
def createOrReplaceTempView(viewName: String): Unit = withPlan {
- createViewCommand(viewName, replace = true)
+ createTempViewCommand(viewName, replace = true, global = false)
}
- private def createViewCommand(viewName: String, replace: Boolean):
CreateViewCommand = {
+ /**
+ * Creates a global temporary view using the given name. The lifetime of
this
+ * temporary view is tied to this Spark application.
+ *
+ * Global temporary view is cross-session. Its lifetime is the lifetime
of the Spark application,
+ * i.e. it will be automatically dropped when the application
terminates. It's tied to a system
+ * preserved database `_global_temp`, and we must use the qualified name
to refer a global temp
+ * view, e.g. `SELECT * FROM _global_temp.view1`.
+ *
+ * @throws TempTableAlreadyExistsException if the view name already
exists
+ *
+ * @group basic
+ * @since 2.1.0
+ */
+ @throws[AnalysisException]
+ def createGlobalTempView(viewName: String): Unit = withPlan {
+ createTempViewCommand(viewName, replace = false, global = true)
--- End diff --
```Scala
Seq(1 -> "a").toDF("i", "j").createGlobalTempView(s"$globalTempDB.src")
checkAnswer(spark.table(s"$globalTempDB.src"), Row(1, "a"))
```
This will fail. Do we allow users to specify the global temp database name?
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