Github user dilipbiswal commented on a diff in the pull request:
https://github.com/apache/spark/pull/12703#discussion_r61129992
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/command/commands.scala
---
@@ -112,3 +116,107 @@ case class ExplainCommand(
("Error occurred during query planning: \n" +
cause.getMessage).split("\n").map(Row(_))
}
}
+
+/**
+ * A command that lists column names of a given table.
+ *
+ * The syntax of using this command in SQL is:
+ * {{{
+ * SHOW COLUMNS (FROM | IN) table_identifier [(FROM | IN) database];
+ * }}}
+ */
+case class ShowColumnsCommand(table: TableIdentifier) extends
RunnableCommand {
+ // The result of SHOW COLUMNS has one column called 'result'
+ override val output: Seq[Attribute] = {
+ AttributeReference("result", StringType, nullable = false)() :: Nil
+ }
+
+ override def run(sparkSession: SparkSession): Seq[Row] = {
+ sparkSession.sessionState.catalog.getTableMetadata(table).schema.map(c
=> Row(c.name))
+ }
+}
+
+/**
+ * A command that lists the partition names of a given table. If the
partition spec is specified,
+ * partitions that match the spec are returned. [[AnalysisException]] is
thrown under the following
+ * conditions:
+ *
+ * 1. If the command is called for a non partitioned table.
+ * 2. If the partition spec refers to the columns that are not defined as
partitioning columns.
+ *
+ * This function creates a [[ShowPartitionsCommand]] logical plan
+ *
+ * The syntax of using this command in SQL is:
+ * {{{
+ * SHOW PARTITIONS [db_name.]table_name [PARTITION(partition_spec)]
+ * }}}
+ */
+case class ShowPartitionsCommand(
+ table: TableIdentifier,
+ spec: Option[TablePartitionSpec]) extends RunnableCommand {
+ // The result of SHOW PARTITIONS has one column called 'result'
+ override val output: Seq[Attribute] = {
+ AttributeReference("result", StringType, nullable = false)() :: Nil
+ }
+
+ private def getPartName(spec: TablePartitionSpec, partitionColumns:
Seq[String]): String = {
+ partitionColumns.map { col =>
+ PartitioningUtils.escapePathName(col) + "=" +
PartitioningUtils.escapePathName(spec(col))
+ }.mkString("/")
--- End diff --
I was using File.separator here. Isn't that more portable ? Or its always
guaranteed to be a back slash ?
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