[GitHub] [incubator-doris] HangyuanLiu commented on a change in pull request #3739: Support materialized view schema change

[GitBox <gi...@apache.org>]

HangyuanLiu commented on a change in pull request #3739:
URL: https://github.com/apache/incubator-doris/pull/3739#discussion_r438032236



##########
File path: be/src/olap/schema_change.cpp
##########
@@ -266,6 +260,92 @@ bool RowBlockChanger::change_row_block(
         int32_t ref_column = _schema_mapping[i].ref_column;
 
         if (_schema_mapping[i].ref_column >= 0) {
+            if (!_schema_mapping[i].materialized_function.empty()) {
+                VLOG(3) << "_schema_mapping[" << i << "].materialized_function : " << _schema_mapping[i].materialized_function;
+                // 效率低下，也可以直接计算变长域拷贝，但仍然会破坏封装
+                for (size_t row_index = 0, new_row_index = 0;
+                     row_index < ref_block->row_block_info().row_num; ++row_index) {
+                    // 不需要的row，每次处理到这个row时就跳过
+                    if (need_filter_data && is_data_left_vec[row_index] == 0) {
+                        continue;
+                    }
+
+                    // 指定新的要写入的row index（不同于读的row_index）
+                    mutable_block->get_row(new_row_index++, &write_helper);
+                    ref_block->get_row(row_index, &read_helper);
+
+                    if (_schema_mapping[i].materialized_function == "to_bitmap") {
+                        write_helper.set_not_null(i);
+                        BitmapValue bitmap;
+                        if (!read_helper.is_null(ref_column)) {

Review comment:
       the result of to_bitmap or hll_hash always not null




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