spark DescribeColumnExec 源码
spark DescribeColumnExec 代码
文件路径：/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/DescribeColumnExec.scala
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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
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* 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.
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package org.apache.spark.sql.execution.datasources.v2
import scala.collection.mutable.ArrayBuffer
import org.apache.spark.sql.catalyst.InternalRow
import org.apache.spark.sql.catalyst.expressions.Attribute
import org.apache.spark.sql.catalyst.util.CharVarcharUtils
case class DescribeColumnExec(
override val output: Seq[Attribute],
column: Attribute,
isExtended: Boolean) extends LeafV2CommandExec {
override protected def run(): Seq[InternalRow] = {
val rows = new ArrayBuffer[InternalRow]()
val comment = if (column.metadata.contains("comment")) {
column.metadata.getString("comment")
} else {
"NULL"
}
rows += toCatalystRow("col_name", column.name)
rows += toCatalystRow("data_type",
CharVarcharUtils.getRawType(column.metadata).getOrElse(column.dataType).catalogString)
rows += toCatalystRow("comment", comment)
// TODO: The extended description (isExtended = true) can be added here.
rows.toSeq
}
}
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