spark view 源码
spark view 代码
文件路径：/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/view.scala
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.spark.sql.catalyst.analysis
import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, View}
import org.apache.spark.sql.catalyst.rules.Rule
/**
* This file defines view types and analysis rules related to views.
*/
/**
* This rule removes [[View]] operators from the plan. The operator is respected till the end of
* analysis stage because we want to see which part of an analyzed logical plan is generated from a
* view.
*/
object EliminateView extends Rule[LogicalPlan] with CastSupport {
override def apply(plan: LogicalPlan): LogicalPlan = plan transformUp {
case View(_, _, child) => child
}
}
/**
* ViewType is used to specify the expected view type when we want to create or replace a view in
* [[CreateViewStatement]].
*/
sealed trait ViewType {
override def toString: String = getClass.getSimpleName.stripSuffix("$")
}
/**
* LocalTempView means session-scoped local temporary views. 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.
*/
object LocalTempView extends ViewType
/**
* GlobalTempView means cross-session global temporary views. 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.
*/
object GlobalTempView extends ViewType
/**
* PersistedView means cross-session persisted views. Persisted views stay until they are
* explicitly dropped by user command. It's always tied to a database, default to the current
* database if not specified.
*
* Note that, Existing persisted view with the same name are not visible to the current session
* while the local temporary view exists, unless the view name is qualified by database.
*/
object PersistedView extends ViewType
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