[SPARK-33081][SQL] Support ALTER TABLE in JDBC v2 Table Catalog: update type and nullability of columns (DB2 dialect)

external/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/v2/DB2IntegrationSuite.scala

@@ -0,0 +1,113 @@
+/*
+ * 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.spark.sql.jdbc.v2
+
+import java.sql.Connection
+
+import org.scalatest.time.SpanSugar._
+
+import org.apache.spark.SparkConf
+import org.apache.spark.sql.AnalysisException
+import org.apache.spark.sql.catalyst.parser.ParseException
+import org.apache.spark.sql.execution.datasources.v2.jdbc.JDBCTableCatalog
+import org.apache.spark.sql.jdbc.{DatabaseOnDocker, DockerJDBCIntegrationSuite}
+import org.apache.spark.sql.test.SharedSparkSession
+import org.apache.spark.sql.types._
+import org.apache.spark.tags.DockerTest
+
+/**
+ * To run this test suite for a specific version (e.g., ibmcom/db2:11.5.4.0):
+ * {{{
+ *   DB2_DOCKER_IMAGE_NAME=ibmcom/db2:11.5.4.0
+ *     ./build/sbt -Pdocker-integration-tests "test-only *DB2IntegrationSuite"
+ * }}}
+ */
+@DockerTest
+class DB2IntegrationSuite extends DockerJDBCIntegrationSuite with SharedSparkSession {
+  override val db = new DatabaseOnDocker {
+    override val imageName = sys.env.getOrElse("DB2_DOCKER_IMAGE_NAME", "ibmcom/db2:11.5.4.0")
+    override val env = Map(
+      "DB2INST1_PASSWORD" -> "rootpass",
+      "LICENSE" -> "accept",
+      "DBNAME" -> "foo",
+      "ARCHIVE_LOGS" -> "false",
+      "AUTOCONFIG" -> "false"
+    )
+    override val usesIpc = false
+    override val jdbcPort: Int = 50000
+    override val privileged = true
+    override def getJdbcUrl(ip: String, port: Int): String =
+      s"jdbc:db2://$ip:$port/foo:user=db2inst1;password=rootpass;retrieveMessagesFromServerOnGetMessage=true;" //scalastyle:ignore
+  }
+
+  override def sparkConf: SparkConf = super.sparkConf
+    .set("spark.sql.catalog.db2", classOf[JDBCTableCatalog].getName)
+    .set("spark.sql.catalog.db2.url", db.getJdbcUrl(dockerIp, externalPort))
+
+  override def dataPreparation(conn: Connection): Unit = {}
+
+  test("SPARK-33034: ALTER TABLE ... update column type") {
+    withTable("db2.alt_table") {
+      sql("CREATE TABLE db2.alt_table (ID INTEGER) USING _")
+      sql("ALTER TABLE db2.alt_table ALTER COLUMN id TYPE DOUBLE")
+      val t = spark.table("db2.alt_table")
+      val expectedSchema = new StructType().add("ID", DoubleType)
+      assert(t.schema === expectedSchema)
+      // Update column type from DOUBLE to STRING
+      val msg1 = intercept[AnalysisException] {
+        sql("ALTER TABLE db2.alt_table ALTER COLUMN id TYPE VARCHAR(10)")
+      }.getMessage
+      assert(msg1.contains("Cannot update alt_table field ID: double cannot be cast to varchar"))
+      // Update not existing column
+      val msg2 = intercept[AnalysisException] {
+        sql("ALTER TABLE db2.alt_table ALTER COLUMN bad_column TYPE DOUBLE")
+      }.getMessage
+      assert(msg2.contains("Cannot update missing field bad_column"))
+      // Update column to wrong type
+      val msg3 = intercept[ParseException] {
+        sql("ALTER TABLE db2.alt_table ALTER COLUMN id TYPE bad_type")
+      }.getMessage
+      assert(msg3.contains("DataType bad_type is not supported"))
+    }
+    // Update column type in not existing table
+    val msg = intercept[AnalysisException] {
+      sql(s"ALTER TABLE db2.not_existing_table ALTER COLUMN id TYPE DOUBLE")
+    }.getMessage
+    assert(msg.contains("Table not found"))
+  }
+
+  test("SPARK-33034: ALTER TABLE ... update column nullability") {
+    withTable("db2.alt_table") {
+      sql("CREATE TABLE db2.alt_table (ID STRING NOT NULL) USING _")
+      sql("ALTER TABLE db2.alt_table ALTER COLUMN ID DROP NOT NULL")
+      val t = spark.table("db2.alt_table")
+      val expectedSchema = new StructType().add("ID", StringType, nullable = true)
+      assert(t.schema === expectedSchema)
+      // Update nullability of not existing column
+      val msg = intercept[AnalysisException] {
+        sql("ALTER TABLE db2.alt_table ALTER COLUMN bad_column DROP NOT NULL")
+      }.getMessage
+      assert(msg.contains("Cannot update missing field bad_column"))
+    }
+    // Update column nullability in not existing table
+    val msg = intercept[AnalysisException] {
+      sql(s"ALTER TABLE db2.not_existing_table ALTER COLUMN ID DROP NOT NULL")
+    }.getMessage
+    assert(msg.contains("Table not found"))
+  }
+}

sql/core/src/main/scala/org/apache/spark/sql/jdbc/DB2Dialect.scala

@@ -58,4 +58,24 @@ private object DB2Dialect extends JdbcDialect {
   override def renameTable(oldTable: String, newTable: String): String = {
     s"RENAME TABLE $oldTable TO $newTable"
   }
+
+  // scalastyle:off line.size.limit
+  // See https://www.ibm.com/support/knowledgecenter/en/SSEPGG_11.5.0/com.ibm.db2.luw.sql.ref.doc/doc/r0000888.html
+  // scalastyle:on line.size.limit
+  override def getUpdateColumnTypeQuery(
+      tableName: String,
+      columnName: String,
+      newDataType: String): String =
+    s"ALTER TABLE $tableName ALTER COLUMN $columnName SET DATA TYPE $newDataType"
+
+  // scalastyle:off line.size.limit
+  // See https://www.ibm.com/support/knowledgecenter/en/SSEPGG_11.5.0/com.ibm.db2.luw.sql.ref.doc/doc/r0000888.html
+  // scalastyle:on line.size.limit
+  override def getUpdateColumnNullabilityQuery(
+      tableName: String,
+      columnName: String,
+      isNullable: Boolean): String = {
+    val nullable = if (isNullable) "DROP NOT NULL" else "SET NOT NULL"
+    s"ALTER TABLE $tableName ALTER COLUMN $columnName $nullable"
+  }
 }