| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you 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. |
| |
| #pragma once |
| |
| #include "common/status.h" |
| #include "format_v2/file_reader.h" |
| |
| namespace doris::format { |
| |
| // Build a projected file-local semantic schema node from a full schema node and a nested |
| // LocalColumnIndex projection. |
| // |
| // This module is deliberately about semantic ColumnDefinition trees, not physical file-format |
| // trees. FileReader::get_schema() returns file-local columns after type conversion to Doris |
| // DataType, and their children must follow Doris semantics: |
| // |
| // STRUCT children = fields |
| // ARRAY children = [element] |
| // MAP children = [key, value] |
| // |
| // Format-specific wrappers, such as Parquet MAP key_value/entry nodes, are intentionally hidden |
| // from this API. A format reader that needs those wrappers for its physical reader tree should |
| // translate the semantic projection back to its physical layout internally. |
| // |
| // The function does three things: |
| // - Copies `field` metadata to `projected_field`. |
| // - Recursively prunes children according to `projection.children`, matching children by |
| // ColumnDefinition::file_local_id() rather than vector ordinal. The root projection id is not |
| // interpreted here because the caller has already selected `field`. |
| // - Rebuilds the node DataType from the projected semantic children so the returned definition is |
| // self-consistent. STRUCT uses projected child names/types, ARRAY uses the projected element |
| // type, and MAP preserves the original key type while rebuilding the projected value type. |
| // |
| // A full projection copies `field` unchanged. Partial MAP projection only uses the value child for |
| // type rebuilding. MAP is materialized as offsets + keys + values, so the reader must still read |
| // the complete key stream to build entry shape and offsets. If the semantic projection includes |
| // the key child, it is ignored here; key-only MAP projections are rejected because they do not |
| // define a value shape. |
| Status project_column_definition(const ColumnDefinition& field, const LocalColumnIndex& projection, |
| ColumnDefinition* projected_field); |
| |
| } // namespace doris::format |
