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/*
* 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.hive.execution
import scala.util.control.NonFatal
import org.apache.spark.sql.{AnalysisException, Row, SQLContext}
import org.apache.spark.sql.catalyst.TableIdentifier
import org.apache.spark.sql.catalyst.catalog.{CatalogColumn, CatalogTable}
import org.apache.spark.sql.catalyst.expressions.Alias
import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, Project}
import org.apache.spark.sql.execution.command.RunnableCommand
import org.apache.spark.sql.hive.{ HiveContext, HiveMetastoreTypes, SQLBuilder}
/**
* Create Hive view on non-hive-compatible tables by specifying schema ourselves instead of
* depending on Hive meta-store.
*/
// TODO: Note that this class can NOT canonicalize the view SQL string entirely, which is different
// from Hive and may not work for some cases like create view on self join.
private[hive] case class CreateViewAsSelect(
tableDesc: CatalogTable,
child: LogicalPlan,
allowExisting: Boolean,
orReplace: Boolean) extends RunnableCommand {
private val childSchema = child.output
assert(tableDesc.schema == Nil || tableDesc.schema.length == childSchema.length)
assert(tableDesc.viewText.isDefined)
private val tableIdentifier = tableDesc.identifier
override def run(sqlContext: SQLContext): Seq[Row] = {
val hiveContext = sqlContext.asInstanceOf[HiveContext]
hiveContext.sessionState.catalog.tableExists(tableIdentifier) match {
case true if allowExisting =>
// Handles `CREATE VIEW IF NOT EXISTS v0 AS SELECT ...`. Does nothing when the target view
// already exists.
case true if orReplace =>
// Handles `CREATE OR REPLACE VIEW v0 AS SELECT ...`
hiveContext.metadataHive.alertView(prepareTable(sqlContext))
case true =>
// Handles `CREATE VIEW v0 AS SELECT ...`. Throws exception when the target view already
// exists.
throw new AnalysisException(s"View $tableIdentifier already exists. " +
"If you want to update the view definition, please use ALTER VIEW AS or " +
"CREATE OR REPLACE VIEW AS")
case false =>
hiveContext.metadataHive.createView(prepareTable(sqlContext))
}
Seq.empty[Row]
}
private def prepareTable(sqlContext: SQLContext): CatalogTable = {
val expandedText = if (sqlContext.conf.canonicalView) {
try rebuildViewQueryString(sqlContext) catch {
case NonFatal(e) => wrapViewTextWithSelect
}
} else {
wrapViewTextWithSelect
}
val viewSchema = {
if (tableDesc.schema.isEmpty) {
childSchema.map { a =>
CatalogColumn(a.name, HiveMetastoreTypes.toMetastoreType(a.dataType))
}
} else {
childSchema.zip(tableDesc.schema).map { case (a, col) =>
CatalogColumn(
col.name,
HiveMetastoreTypes.toMetastoreType(a.dataType),
nullable = true,
col.comment)
}
}
}
tableDesc.copy(schema = viewSchema, viewText = Some(expandedText))
}
private def wrapViewTextWithSelect: String = {
// When user specified column names for view, we should create a project to do the renaming.
// When no column name specified, we still need to create a project to declare the columns
// we need, to make us more robust to top level `*`s.
val viewOutput = {
val columnNames = childSchema.map(f => quote(f.name))
if (tableDesc.schema.isEmpty) {
columnNames.mkString(", ")
} else {
columnNames.zip(tableDesc.schema.map(f => quote(f.name))).map {
case (name, alias) => s"$name AS $alias"
}.mkString(", ")
}
}
val viewText = tableDesc.viewText.get
val viewName = quote(tableDesc.identifier.table)
s"SELECT $viewOutput FROM ($viewText) $viewName"
}
private def rebuildViewQueryString(sqlContext: SQLContext): String = {
val logicalPlan = if (tableDesc.schema.isEmpty) {
child
} else {
val projectList = childSchema.zip(tableDesc.schema).map {
case (attr, col) => Alias(attr, col.name)()
}
sqlContext.executePlan(Project(projectList, child)).analyzed
}
new SQLBuilder(logicalPlan, sqlContext).toSQL
}
// escape backtick with double-backtick in column name and wrap it with backtick.
private def quote(name: String) = s"`${name.replaceAll("`", "``")}`"
}
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