Fix failure when reading missing fields in Parquet

Author: ebyhr

lib/trino-parquet/src/main/java/io/trino/parquet/reader/ParquetReader.java

@@ -337,7 +337,11 @@ private ColumnChunk readArray(GroupField field)
     {
         List<Type> parameters = field.getType().getTypeParameters();
         checkArgument(parameters.size() == 1, "Arrays must have a single type parameter, found %s", parameters.size());
-        Field elementField = field.getChildren().get(0).get();
+        Optional<Field> children = field.getChildren().get(0);
+        if (children.isEmpty()) {
+            return new ColumnChunk(field.getType().createNullBlock(), new int[] {}, new int[] {});
+        }
+        Field elementField = children.get();
         ColumnChunk columnChunk = readColumnChunk(elementField);
 
         ListColumnReader.BlockPositions collectionPositions = calculateCollectionOffsets(field, columnChunk.getDefinitionLevels(), columnChunk.getRepetitionLevels());
@@ -355,7 +359,8 @@ private ColumnChunk readMap(GroupField field)
 
         ColumnChunk columnChunk = readColumnChunk(field.getChildren().get(0).get());
         blocks[0] = columnChunk.getBlock();
-        blocks[1] = readColumnChunk(field.getChildren().get(1).get()).getBlock();
+        Optional<Field> valueField = field.getChildren().get(1);
+        blocks[1] = valueField.isPresent() ? readColumnChunk(valueField.get()).getBlock() : parameters.get(1).createNullBlock();
         ListColumnReader.BlockPositions collectionPositions = calculateCollectionOffsets(field, columnChunk.getDefinitionLevels(), columnChunk.getRepetitionLevels());
         Block mapBlock = ((MapType) field.getType()).createBlockFromKeyValue(collectionPositions.isNull(), collectionPositions.offsets(), blocks[0], blocks[1]);
         return new ColumnChunk(mapBlock, columnChunk.getDefinitionLevels(), columnChunk.getRepetitionLevels());

plugin/trino-iceberg/src/test/java/io/trino/plugin/iceberg/BaseIcebergConnectorTest.java

@@ -8539,6 +8539,45 @@ public void testSetIllegalExtraPropertyKey()
         }
     }
 
+    @Test // regression test for https://github.com/trinodb/trino/issues/22922
+    void testArrayElementChange()
+    {
+        try (TestTable table = new TestTable(
+                getQueryRunner()::execute,
+                "test_array_schema_change",
+                "(col array(row(a varchar, b varchar)))",
+                List.of("CAST(array[row('a', 'b')] AS array(row(a varchar, b varchar)))"))) {
+            assertUpdate("ALTER TABLE " + table.getName() + " DROP COLUMN col.element.a");
+            assertUpdate("ALTER TABLE " + table.getName() + " ADD COLUMN col.element.c varchar");
+            assertUpdate("ALTER TABLE " + table.getName() + " DROP COLUMN col.element.b");
+
+            String expected = format == ORC ? "CAST(array[row(NULL)] AS array(row(c varchar)))" : "CAST(NULL AS array(row(c varchar)))";
+            assertThat(query("SELECT * FROM " + table.getName()))
+                    .matches("VALUES " + expected);
+        }
+    }
+
+    // MAP type is tested in TestIcebergV2.testMapValueSchemaChange
+
+    @Test
+    void testRowFieldChange()
+    {
+        try (TestTable table = new TestTable(
+                getQueryRunner()::execute,
+                "test_row_schema_change",
+                "(col row(a varchar, b varchar))")) {
+            assertUpdate("INSERT INTO " + table.getName() + " SELECT CAST(row('a', 'b') AS row(a varchar, b varchar))", 1);
+
+            assertUpdate("ALTER TABLE " + table.getName() + " DROP COLUMN col.a");
+            assertUpdate("ALTER TABLE " + table.getName() + " ADD COLUMN col.c varchar");
+            assertUpdate("ALTER TABLE " + table.getName() + " DROP COLUMN col.b");
+
+            String expected = format == ORC || format == AVRO ? "CAST(row(NULL) AS row(c varchar))" : "CAST(NULL AS row(c varchar))";
+            assertThat(query("SELECT * FROM " + table.getName()))
+                    .matches("SELECT " + expected);
+        }
+    }
+
     @Test
     public void testObjectStoreLayoutEnabledAndDataLocation()
             throws Exception

plugin/trino-iceberg/src/test/java/io/trino/plugin/iceberg/TestIcebergV2.java

@@ -1466,6 +1466,31 @@ public void testHighlyNestedFieldPartitioningWithTimestampTransform()
                 ImmutableSet.of("grandparent.parent.ts_hour=2021-01-01-01/", "grandparent.parent.ts_hour=2022-02-02-02/", "grandparent.parent.ts_hour=2023-03-03-03/"));
     }
 
+    @Test
+    void testMapValueSchemaChange()
+    {
+        testMapValueSchemaChange("PARQUET", "map(array[1], array[NULL])");
+        testMapValueSchemaChange("ORC", "map(array[1], array[row(NULL)])");
+        testMapValueSchemaChange("AVRO", "NULL");
+    }
+
+    private void testMapValueSchemaChange(String format, String expectedValue)
+    {
+        try (TestTable table = new TestTable(
+                getQueryRunner()::execute,
+                "test_map_value_schema_change",
+                "WITH (format = '" + format + "') AS SELECT CAST(map(array[1], array[row(2)]) AS map(integer, row(field integer))) col")) {
+            Table icebergTable = loadTable(table.getName());
+            icebergTable.updateSchema()
+                    .addColumn("col.value", "new_field", Types.IntegerType.get())
+                    .deleteColumn("col.value.field")
+                    .commit();
+            assertThat(query("SELECT * FROM " + table.getName()))
+                    .as("Format: %s", format)
+                    .matches("SELECT CAST(" + expectedValue + " AS map(integer, row(new_field integer)))");
+        }
+    }
+
     @Test
     public void testUpdateAfterEqualityDelete()
             throws Exception