branch-4.1: [feat] add Parquet metadata TVF #58972

be/src/vec/exec/format/table/parquet_metadata_reader.h

@@ -0,0 +1,82 @@
+// 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 <gen_cpp/PlanNodes_types.h>
+
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "common/factory_creator.h"
+#include "common/status.h"
+#include "runtime/descriptors.h"
+#include "vec/exec/format/generic_reader.h"
+
+namespace doris {
+class RuntimeProfile;
+class RuntimeState;
+namespace io {
+class FileReader;
+} // namespace io
+} // namespace doris
+
+namespace doris::vectorized {
+class Block;
+
+// Lightweight reader that surfaces Parquet footer metadata as a table-valued scan.
+// It reads only file footers (no data pages) and emits either schema rows or
+// row-group/column statistics based on `mode`.
+class ParquetMetadataReader : public GenericReader {
+    ENABLE_FACTORY_CREATOR(ParquetMetadataReader);
+
+public:
+    class ModeHandler;
+
+    ParquetMetadataReader(std::vector<SlotDescriptor*> slots, RuntimeState* state,
+                          RuntimeProfile* profile, TMetaScanRange scan_range);
+    ~ParquetMetadataReader() override;
+
+    Status init_reader();
+    Status get_next_block(Block* block, size_t* read_rows, bool* eof) override;
+    Status close() override;
+
+private:
+    Status _init_from_scan_range(const TMetaScanRange& scan_range);
+    Status _build_rows(std::vector<MutableColumnPtr>& columns);
+    Status _append_file_rows(const std::string& path, std::vector<MutableColumnPtr>& columns);
+
+    enum class Mode { SCHEMA, METADATA, FILE_METADATA, KEY_VALUE_METADATA, BLOOM_PROBE };
+
+    RuntimeState* _state = nullptr;
+    std::vector<SlotDescriptor*> _slots;
+    TMetaScanRange _scan_range;
+    std::vector<std::string> _paths;
+    // File system type and properties for remote Parquet access.
+    TFileType::type _file_type = TFileType::FILE_LOCAL;
+    std::map<std::string, std::string> _properties;
+    std::string _mode;
+    Mode _mode_type = Mode::METADATA;
+    std::string _bloom_column;
+    std::string _bloom_literal;
+    bool _eof = false;
+    std::unique_ptr<ModeHandler> _mode_handler;
+};
+
+} // namespace doris::vectorized