Github user gengliangwang commented on a diff in the pull request:
https://github.com/apache/spark/pull/20020#discussion_r158200471
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/command/DataWritingCommand.scala
---
@@ -20,30 +20,32 @@ package org.apache.spark.sql.execution.command
import org.apache.hadoop.conf.Configuration
import org.apache.spark.SparkContext
-import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
+import org.apache.spark.sql.{Row, SparkSession}
+import org.apache.spark.sql.catalyst.expressions.Attribute
+import org.apache.spark.sql.catalyst.plans.logical.{AnalysisBarrier,
Command, LogicalPlan}
+import org.apache.spark.sql.execution.SparkPlan
import org.apache.spark.sql.execution.datasources.BasicWriteJobStatsTracker
+import org.apache.spark.sql.execution.datasources.FileFormatWriter
import org.apache.spark.sql.execution.metric.{SQLMetric, SQLMetrics}
import org.apache.spark.util.SerializableConfiguration
-
/**
* A special `RunnableCommand` which writes data out and updates metrics.
*/
-trait DataWritingCommand extends RunnableCommand {
-
+trait DataWritingCommand extends Command {
/**
* The input query plan that produces the data to be written.
+ * IMPORTANT: the input query plan MUST be analyzed, so that we can
carry its output columns
+ * to [[FileFormatWriter]].
*/
def query: LogicalPlan
- // We make the input `query` an inner child instead of a child in order
to hide it from the
- // optimizer. This is because optimizer may not preserve the output
schema names' case, and we
- // have to keep the original analyzed plan here so that we can pass the
corrected schema to the
- // writer. The schema of analyzed plan is what user expects(or
specifies), so we should respect
- // it when writing.
- override protected def innerChildren: Seq[LogicalPlan] = query :: Nil
+ override def children: Seq[LogicalPlan] = query :: Nil
--- End diff --
I tried but it will cause runtime exception. When the `AnalysisBarrier` is
removed by analyzer, the child of `DataWritingCommand` is no longer
`AnalysisBarrier`
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