[GitHub] [doris] amorynan commented on a diff in pull request #17330: [Refactor](map) remove using column array in map to reduce offset column

["amorynan (via GitHub)" <gi...@apache.org>]

amorynan commented on code in PR #17330:
URL: https://github.com/apache/doris/pull/17330#discussion_r1122840277


##########
be/src/vec/olap/olap_data_convertor.cpp:
##########
@@ -810,30 +808,52 @@ Status OlapBlockDataConvertor::OlapColumnDataConvertorMap::convert_to_olap(
         const ColumnMap* column_map, const DataTypeMap* data_type_map) {
     ColumnPtr key_data = column_map->get_keys_ptr();
     ColumnPtr value_data = column_map->get_values_ptr();
+    const UInt8* key_null_map = nullptr;
+    const UInt8* val_null_map = nullptr;
     if (column_map->get_keys().is_nullable()) {
         const auto& key_nullable_column =
                 assert_cast<const ColumnNullable&>(column_map->get_keys());
         key_data = key_nullable_column.get_nested_column_ptr();
+        key_null_map = key_nullable_column.get_null_map_data().data();
     }
 
     if (column_map->get_values().is_nullable()) {
         const auto& val_nullable_column =
                 assert_cast<const ColumnNullable&>(column_map->get_values());
         value_data = val_nullable_column.get_nested_column_ptr();
+        val_null_map = val_nullable_column.get_null_map_data().data();
     }
 
-    ColumnWithTypeAndName key_typed_column = {key_data, remove_nullable(data_type_map->get_keys()),
-                                              "map.key"};
-    _key_convertor->set_source_column(key_typed_column, _row_pos, _num_rows);
+    // offsets data
+    auto& offsets = column_map->get_offsets();
+    // make first offset
+    auto offsets_col = ColumnArray::ColumnOffsets::create();
+
+    _offsets.reserve(offsets.size() + 1);
+    _offsets.push_back(_row_pos);
+    _offsets.insert_assume_reserved(offsets.begin(), offsets.end());
+
+    int64_t start_index = _row_pos - 1;
+    int64_t end_index = _row_pos + _num_rows - 1;
+    auto start = offsets[start_index];
+    auto size = offsets[end_index] - start;
+
+    ColumnWithTypeAndName key_typed_column = {
+            key_data, remove_nullable(data_type_map->get_key_type()), "map.key"};
+    _key_convertor->set_source_column(key_typed_column, start, size);
     _key_convertor->convert_to_olap();
 
     ColumnWithTypeAndName value_typed_column = {
-            value_data, remove_nullable(data_type_map->get_values()), "map.value"};
-    _value_convertor->set_source_column(value_typed_column, _row_pos, _num_rows);
+            value_data, remove_nullable(data_type_map->get_value_type()), "map.value"};
+    _value_convertor->set_source_column(value_typed_column, start, size);
     _value_convertor->convert_to_olap();
 
-    _results[0] = _key_convertor->get_data();
-    _results[1] = _value_convertor->get_data();
+    _results[0] = (void*)size;
+    _results[1] = _offsets.data();
+    _results[2] = _key_convertor->get_data();

Review Comment:
   I think this order is more convenience  go through for k data and nullmap  and   v data and nullmap   one by one in column_writer , I will reorder this misleading annotate.



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