[GitHub] [spark] viirya commented on a change in pull request #24938: [SPARK-27946][SQL] Hive DDL to Spark DDL conversion USING "show create table"

[GitBox <gi...@apache.org>]

viirya commented on a change in pull request #24938: [SPARK-27946][SQL] Hive DDL to Spark DDL conversion USING "show create table"
URL: https://github.com/apache/spark/pull/24938#discussion_r310273634
 
 

 ##########
 File path: sql/core/src/main/scala/org/apache/spark/sql/execution/command/tables.scala
 ##########
 @@ -1057,83 +1143,86 @@ case class ShowCreateTableCommand(table: TableIdentifier) extends RunnableComman
       }
     }
   }
+}
 
-  private def showTableLocation(metadata: CatalogTable, builder: StringBuilder): Unit = {
-    if (metadata.tableType == EXTERNAL) {
-      metadata.storage.locationUri.foreach { location =>
-        builder ++= s"LOCATION '${escapeSingleQuotedString(CatalogUtils.URIToString(location))}'\n"
-      }
-    }
-  }
+/**
+ * This commands generates Spark DDL for Hive table.
+ *
+ * The syntax of using this command in SQL is:
+ * {{{
+ *   SHOW CREATE TABLE table_identifier AS SPARK;
+ * }}}
+ */
+case class ShowCreateTableAsSparkCommand(table: TableIdentifier)
+    extends RunnableCommand with ShowCreateTableCommandBase {
+  override val output: Seq[Attribute] = Seq(
+    AttributeReference("sparktab_stmt", StringType, nullable = false)()
+  )
 
-  private def showTableComment(metadata: CatalogTable, builder: StringBuilder): Unit = {
-    metadata
-      .comment
-      .map("COMMENT '" + escapeSingleQuotedString(_) + "'\n")
-      .foreach(builder.append)
-  }
+  override def run(sparkSession: SparkSession): Seq[Row] = {
+    val catalog = sparkSession.sessionState.catalog
+    val tableMetadata = catalog.getTableMetadata(table)
 
-  private def showTableProperties(metadata: CatalogTable, builder: StringBuilder): Unit = {
-    if (metadata.properties.nonEmpty) {
-      val props = metadata.properties.map { case (key, value) =>
-        s"'${escapeSingleQuotedString(key)}' = '${escapeSingleQuotedString(value)}'"
+    val stmt = if (DDLUtils.isDatasourceTable(tableMetadata)) {
+      throw new AnalysisException(
+        s"$table is already a Spark data source table. Use `SHOW CREATE TABLE` instead.")
+    } else {
+      if (tableMetadata.unsupportedFeatures.nonEmpty) {
+        throw new AnalysisException(
+          "Failed to execute SHOW CREATE TABLE AS SPARK against table " +
+            s"${tableMetadata.identifier}, which is created by Hive and uses the " +
+            "following unsupported feature(s)\n" +
+            tableMetadata.unsupportedFeatures.map(" - " + _).mkString("\n")
+        )
       }
 
-      builder ++= props.mkString("TBLPROPERTIES (\n  ", ",\n  ", "\n)\n")
-    }
-  }
-
-  private def showCreateDataSourceTable(metadata: CatalogTable): String = {
-    val builder = StringBuilder.newBuilder
-
-    builder ++= s"CREATE TABLE ${table.quotedString} "
-    showDataSourceTableDataColumns(metadata, builder)
-    showDataSourceTableOptions(metadata, builder)
-    showDataSourceTableNonDataColumns(metadata, builder)
-    showTableComment(metadata, builder)
-    showTableLocation(metadata, builder)
-    showTableProperties(metadata, builder)
-
-    builder.toString()
-  }
-
-  private def showDataSourceTableDataColumns(
-      metadata: CatalogTable, builder: StringBuilder): Unit = {
-    val columns = metadata.schema.fields.map(_.toDDL)
-    builder ++= columns.mkString("(", ", ", ")\n")
-  }
+      if (tableMetadata.tableType == VIEW) {
+        throw new AnalysisException("Hive view isn't supported by SHOW CREATE TABLE AS SPARK")
+      }
 
-  private def showDataSourceTableOptions(metadata: CatalogTable, builder: StringBuilder): Unit = {
-    builder ++= s"USING ${metadata.provider.get}\n"
+      // scalastyle:off caselocale
+      if (tableMetadata.properties.getOrElse("transactional", "false").toLowerCase.equals("true")) {
 
 Review comment:
   Should we just move the property to `unsupportedFeatures` of `CatalogTable`?

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