[Opt](load) Speed up the vectorized load (#12146)

* [Opt](load) Speed up the vectorized load

be/src/vec/functions/function_helpers.cpp

@@ -26,6 +26,39 @@
 
 namespace doris::vectorized {
 
+Block create_block_with_nested_columns_only_args(const Block& block, const ColumnNumbers& args) {
+    std::set<size_t> args_set(args.begin(), args.end());
+    Block res;
+
+    for (auto i : args_set) {
+        const auto& col = block.get_by_position(i);
+
+        if (col.type->is_nullable()) {
+            const DataTypePtr& nested_type =
+                    static_cast<const DataTypeNullable&>(*col.type).get_nested_type();
+
+            if (!col.column) {
+                res.insert({nullptr, nested_type, col.name});
+            } else if (auto* nullable = check_and_get_column<ColumnNullable>(*col.column)) {
+                const auto& nested_col = nullable->get_nested_column_ptr();
+                res.insert({nested_col, nested_type, col.name});
+            } else if (auto* const_column = check_and_get_column<ColumnConst>(*col.column)) {
+                const auto& nested_col =
+                        check_and_get_column<ColumnNullable>(const_column->get_data_column())
+                                ->get_nested_column_ptr();
+                res.insert({ColumnConst::create(nested_col, col.column->size()), nested_type,
+                            col.name});
+            } else {
+                LOG(FATAL) << "Illegal column for DataTypeNullable";
+            }
+        } else {
+            res.insert(col);
+        }
+    }
+
+    return res;
+}
+
 static Block create_block_with_nested_columns_impl(const Block& block,
                                                    const std::unordered_set<size_t>& args) {
     Block res;