Support comment when adding a new column (ALTER TABLE ADD COLUMN) in Delta Lake

plugin/trino-delta-lake/src/main/java/io/trino/plugin/deltalake/DeltaLakeMetadata.java

@@ -944,10 +944,6 @@ private static boolean isCreatedBy(Table table, String queryId)
     @Override
     public void addColumn(ConnectorSession session, ConnectorTableHandle tableHandle, ColumnMetadata newColumnMetadata)
     {
-        if (newColumnMetadata.getComment() != null) {
-            throw new TrinoException(NOT_SUPPORTED, "This connector does not support adding columns with comments");
-        }
-
         DeltaLakeTableHandle handle = (DeltaLakeTableHandle) tableHandle;
         ConnectorTableMetadata tableMetadata = getTableMetadata(session, handle);
 
@@ -961,6 +957,11 @@ public void addColumn(ConnectorSession session, ConnectorTableHandle tableHandle
                     .map(column -> toColumnHandle(column, partitionColumns))
                     .collect(toImmutableList()));
             columnsBuilder.add(toColumnHandle(newColumnMetadata, partitionColumns));
+            ImmutableMap.Builder<String, String> columnComments = ImmutableMap.builder();
+            columnComments.putAll(getColumnComments(handle.getMetadataEntry()));
+            if (newColumnMetadata.getComment() != null) {
+                columnComments.put(newColumnMetadata.getName(), newColumnMetadata.getComment());
+            }
 
             Optional<Long> checkpointInterval = DeltaLakeTableProperties.getCheckpointInterval(tableMetadata.getProperties());
 
@@ -971,7 +972,7 @@ public void addColumn(ConnectorSession session, ConnectorTableHandle tableHandle
                     handle.getMetadataEntry().getId(),
                     columnsBuilder.build(),
                     partitionColumns,
-                    getColumnComments(handle.getMetadataEntry()),
+                    columnComments.buildOrThrow(),
                     buildDeltaMetadataConfiguration(checkpointInterval),
                     ADD_COLUMN_OPERATION,
                     session,

plugin/trino-delta-lake/src/test/java/io/trino/plugin/deltalake/BaseDeltaLakeMinioConnectorTest.java

@@ -106,7 +106,6 @@ protected boolean hasBehavior(TestingConnectorBehavior connectorBehavior)
             case SUPPORTS_TOPN_PUSHDOWN:
             case SUPPORTS_AGGREGATION_PUSHDOWN:
             case SUPPORTS_RENAME_TABLE:
-            case SUPPORTS_ADD_COLUMN_WITH_COMMENT:
             case SUPPORTS_DROP_COLUMN:
             case SUPPORTS_RENAME_COLUMN:
             case SUPPORTS_COMMENT_ON_TABLE:

testing/trino-product-tests/src/main/java/io/trino/tests/product/deltalake/TestDeltaLakeAlterTableCompatibility.java

@@ -0,0 +1,51 @@
+/*
+ * Licensed 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 io.trino.tests.product.deltalake;
+
+import org.testng.annotations.Test;
+
+import static io.trino.tests.product.TestGroups.DELTA_LAKE_DATABRICKS;
+import static io.trino.tests.product.TestGroups.DELTA_LAKE_OSS;
+import static io.trino.tests.product.TestGroups.PROFILE_SPECIFIC_TESTS;
+import static io.trino.tests.product.deltalake.util.DeltaLakeTestUtils.getColumnCommentOnDelta;
+import static io.trino.tests.product.deltalake.util.DeltaLakeTestUtils.getColumnCommentOnTrino;
+import static io.trino.tests.product.hive.util.TemporaryHiveTable.randomTableSuffix;
+import static io.trino.tests.product.utils.QueryExecutors.onTrino;
+import static java.lang.String.format;
+import static org.testng.Assert.assertEquals;
+
+public class TestDeltaLakeAlterTableCompatibility
+        extends BaseTestDeltaLakeS3Storage
+{
+    @Test(groups = {DELTA_LAKE_DATABRICKS, DELTA_LAKE_OSS, PROFILE_SPECIFIC_TESTS})
+    public void testAddColumnWithCommentOnTrino()
+    {
+        String tableName = "test_dl_add_column_with_comment_" + randomTableSuffix();
+        String tableDirectory = "databricks-compatibility-test-" + tableName;
+
+        onTrino().executeQuery(format("CREATE TABLE delta.default.%s (col INT) WITH (location = 's3://%s/%s')",
+                tableName,
+                bucketName,
+                tableDirectory));
+
+        try {
+            onTrino().executeQuery("ALTER TABLE delta.default." + tableName + " ADD COLUMN new_col INT COMMENT 'new column comment'");
+            assertEquals(getColumnCommentOnTrino("default", tableName, "new_col"), "new column comment");
+            assertEquals(getColumnCommentOnDelta("default", tableName, "new_col"), "new column comment");
+        }
+        finally {
+            onTrino().executeQuery("DROP TABLE delta.default." + tableName);
+        }
+    }
+}

testing/trino-product-tests/src/main/java/io/trino/tests/product/deltalake/TestDeltaLakeDatabricksCreateTableCompatibility.java

@@ -24,6 +24,8 @@
 import static io.trino.tempto.assertions.QueryAssert.assertThat;
 import static io.trino.tests.product.TestGroups.DELTA_LAKE_DATABRICKS;
 import static io.trino.tests.product.TestGroups.PROFILE_SPECIFIC_TESTS;
+import static io.trino.tests.product.deltalake.util.DeltaLakeTestUtils.getColumnCommentOnDelta;
+import static io.trino.tests.product.deltalake.util.DeltaLakeTestUtils.getColumnCommentOnTrino;
 import static io.trino.tests.product.hive.util.TemporaryHiveTable.randomTableSuffix;
 import static io.trino.tests.product.utils.QueryExecutors.onDelta;
 import static io.trino.tests.product.utils.QueryExecutors.onTrino;
@@ -248,16 +250,4 @@ public void testCreateTableWithColumnCommentOnDelta()
             onDelta().executeQuery("DROP TABLE default." + tableName);
         }
     }
-
-    private static String getColumnCommentOnTrino(String schemaName, String tableName, String columnName)
-    {
-        QueryResult result = onTrino().executeQuery("SELECT comment FROM information_schema.columns WHERE table_schema = '" + schemaName + "' AND table_name = '" + tableName + "' AND column_name = '" + columnName + "'");
-        return (String) result.row(0).get(0);
-    }
-
-    private static String getColumnCommentOnDelta(String schemaName, String tableName, String columnName)
-    {
-        QueryResult result = onDelta().executeQuery(format("DESCRIBE %s.%s %s", schemaName, tableName, columnName));
-        return (String) result.row(2).get(1);
-    }
 }

testing/trino-product-tests/src/main/java/io/trino/tests/product/deltalake/util/DeltaLakeTestUtils.java

@@ -0,0 +1,37 @@
+/*
+ * Licensed 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 io.trino.tests.product.deltalake.util;
+
+import io.trino.tempto.query.QueryResult;
+
+import static io.trino.tests.product.utils.QueryExecutors.onDelta;
+import static io.trino.tests.product.utils.QueryExecutors.onTrino;
+import static java.lang.String.format;
+
+public final class DeltaLakeTestUtils
+{
+    private DeltaLakeTestUtils() {}
+
+    public static String getColumnCommentOnTrino(String schemaName, String tableName, String columnName)
+    {
+        QueryResult result = onTrino().executeQuery("SELECT comment FROM information_schema.columns WHERE table_schema = '" + schemaName + "' AND table_name = '" + tableName + "' AND column_name = '" + columnName + "'");
+        return (String) result.row(0).get(0);
+    }
+
+    public static String getColumnCommentOnDelta(String schemaName, String tableName, String columnName)
+    {
+        QueryResult result = onDelta().executeQuery(format("DESCRIBE %s.%s %s", schemaName, tableName, columnName));
+        return (String) result.row(2).get(1);
+    }
+}