Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/11991#discussion_r57541533
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/command/commands.scala
---
@@ -350,6 +358,40 @@ case class ShowTablesCommand(databaseName:
Option[String]) extends RunnableComma
}
/**
+ * A command for users to list the databases/schemas.
+ * If a databasePattern is supplied then the databases that only matches
the
+ * pattern would be listed.
+ * The syntax of using this command in SQL is:
+ * {{{
+ * SHOW (DATABASES|SCHEMAS) [LIKE 'identifier_with_wildcards'];
+ * }}}
+ */
+case class ShowDatabasesCommand(databasePattern: Option[String]) extends
RunnableCommand {
+
+ // The result of SHOW TABLES has two columns, tableName and isTemporary.
+ override val output: Seq[Attribute] = {
+ val schema = StructType(
+ StructField("databaseName", StringType, false) :: Nil)
+
+ schema.toAttributes
+ }
+
+ override def run(sqlContext: SQLContext): Seq[Row] = {
+ // Since we need to return a Seq of rows, we will call getTables
directly
+ // instead of calling tables in sqlContext.
+ val catalog = sqlContext.sessionState.catalog
+ val databases =
+ if (databasePattern.isDefined) {
+ catalog.listDatabases(databasePattern.get)
--- End diff --
indents.
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