[spark] Support show columns in spark (apache#3888)

paimon-spark/paimon-spark-3.2/src/test/scala/org/apache/paimon/spark/sql/ShowColumnsTest.scala

@@ -0,0 +1,21 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.paimon.spark.sql
+
+class ShowColumnsTest extends PaimonShowColumnsTestBase {}

paimon-spark/paimon-spark-3.3/src/test/scala/org/apache/paimon/spark/sql/ShowColumnsTest.scala

@@ -0,0 +1,21 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.paimon.spark.sql
+
+class ShowColumnsTest extends PaimonShowColumnsTestBase {}

paimon-spark/paimon-spark-3.4/src/test/scala/org/apache/paimon/spark/sql/ShowColumnsTest.scala

@@ -0,0 +1,21 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.paimon.spark.sql
+
+class ShowColumnsTest extends PaimonShowColumnsTestBase {}

paimon-spark/paimon-spark-3.5/src/test/scala/org/apache/paimon/spark/sql/ShowColumnsTest.scala

@@ -0,0 +1,21 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.paimon.spark.sql
+
+class ShowColumnsTest extends PaimonShowColumnsTestBase {}

paimon-spark/paimon-spark-common/src/main/scala/org/apache/paimon/spark/catalyst/analysis/PaimonAnalysis.scala

@@ -21,7 +21,7 @@ package org.apache.paimon.spark.catalyst.analysis
 import org.apache.paimon.spark.SparkTable
 import org.apache.paimon.spark.catalyst.Compatibility
 import org.apache.paimon.spark.catalyst.analysis.PaimonRelation.isPaimonTable
-import org.apache.paimon.spark.commands.{PaimonAnalyzeTableColumnCommand, PaimonDynamicPartitionOverwriteCommand, PaimonTruncateTableCommand}
+import org.apache.paimon.spark.commands.{PaimonAnalyzeTableColumnCommand, PaimonDynamicPartitionOverwriteCommand, PaimonShowColumnsCommand, PaimonTruncateTableCommand}
 import org.apache.paimon.table.FileStoreTable
 
 import org.apache.spark.sql.SparkSession
@@ -62,6 +62,9 @@ class PaimonAnalysis(session: SparkSession) extends Rule[LogicalPlan] {
 
     case merge: MergeIntoTable if isPaimonTable(merge.targetTable) && merge.childrenResolved =>
       PaimonMergeIntoResolver(merge, session)
+
+    case s @ ShowColumns(PaimonRelation(table), _, _) if s.resolved =>
+      PaimonShowColumnsCommand(table)
   }
 
   private def needsSchemaAdjustmentByName(

paimon-spark/paimon-spark-common/src/main/scala/org/apache/paimon/spark/commands/PaimonShowColumnsCommand.scala

@@ -0,0 +1,41 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.paimon.spark.commands
+
+import org.apache.paimon.spark.SparkTable
+import org.apache.paimon.spark.leafnode.PaimonLeafRunnableCommand
+import org.apache.paimon.table.FileStoreTable
+
+import org.apache.spark.sql.{Row, SparkSession}
+import org.apache.spark.sql.catalyst.expressions.{Attribute, AttributeReference, GenericRow}
+import org.apache.spark.sql.types.{Metadata, StringType}
+import org.apache.spark.unsafe.types.UTF8String
+
+case class PaimonShowColumnsCommand(v2Table: SparkTable)
+  extends PaimonLeafRunnableCommand
+  with WithFileStoreTable {
+  override def table: FileStoreTable = v2Table.getTable.asInstanceOf[FileStoreTable]
+
+  override lazy val output: Seq[Attribute] = Seq(
+    AttributeReference("column", StringType, true, Metadata.empty)())
+
+  override def run(sparkSession: SparkSession): Seq[Row] = {
+    v2Table.schema.map(sc => new GenericRow(Array[Any](UTF8String.fromString(sc.name)))).toSeq
+  }
+}

paimon-spark/paimon-spark-common/src/test/scala/org/apache/paimon/spark/sql/PaimonShowColumnsTestBase.scala

@@ -0,0 +1,46 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.paimon.spark.sql
+
+import org.apache.paimon.spark.PaimonSparkTestBase
+
+import org.apache.spark.sql.Row
+
+abstract class PaimonShowColumnsTestBase extends PaimonSparkTestBase {
+
+  test("Show columns from Paimon test") {
+    spark.sql(s"""
+                 |CREATE TABLE T (id STRING, name STRING, i INT, l LONG)
+                 |USING PAIMON
+                 |TBLPROPERTIES ('primary-key'='id')
+                 |""".stripMargin)
+
+    spark.sql(
+      s"""
+         |INSERT INTO T SELECT '1', 'aa', 12, 22
+         |""".stripMargin
+    )
+
+    checkAnswer(
+      spark.sql("SHOW COLUMNS FROM T"),
+      Row("id") :: Row("name") :: Row("i") :: Row("l") :: Nil)
+
+  }
+
+}