cloud-fan commented on a change in pull request #26182: [SPARK-29523][SQL] SHOW
COLUMNS should do multi-catalog resolution.
URL: https://github.com/apache/spark/pull/26182#discussion_r339897559
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
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@@ -2911,4 +2911,28 @@ class AstBuilder(conf: SQLConf) extends
SqlBaseBaseVisitor[AnyRef] with Logging
override def visitRefreshTable(ctx: RefreshTableContext): LogicalPlan =
withOrigin(ctx) {
RefreshTableStatement(visitMultipartIdentifier(ctx.multipartIdentifier()))
}
+
+ /**
+ * A command for users to list the column names for a table.
+ * This function creates a [[ShowColumnsStatement]] logical plan.
+ *
+ * The syntax of using this command in SQL is:
+ * {{{
+ * SHOW COLUMNS (FROM | IN) tableName=multipartIdentifier
+ * ((FROM | IN) namespace=multipartIdentifier)?
+ * }}}
+ */
+ override def visitShowColumns(ctx: ShowColumnsContext): LogicalPlan =
withOrigin(ctx) {
+ import org.apache.spark.sql.connector.catalog.CatalogV2Implicits._
+
+ val table = visitMultipartIdentifier(ctx.table)
+ val namespace = Option(ctx.namespace).map(visitMultipartIdentifier)
+ if (namespace.isDefined && namespace.get.length > 1 && table.length > 1) {
Review comment:
OK I get it. Previously we support `SHOW COLUMNS FROM db1.t1 IN db1`, and at
runtime we check if the specified database name is the same as the db name in
table identifier.
Seems like we should move this check into the analyzer, i.e. in
`ResolveSessionCatalog`
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