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// 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. //! Main entrypoint for working with Parquet API. //! //! Provides access to file and row group readers and writers, record API, metadata, etc. //! //! See [`reader::SerializedFileReader`](reader/struct.SerializedFileReader.html) or //! [`writer::SerializedFileWriter`](writer/struct.SerializedFileWriter.html) for a //! starting reference, [`metadata::ParquetMetaData`](metadata/index.html) for file //! metadata, and [`statistics`](statistics/index.html) for working with statistics. //! //! # Example of writing a new file //! //! ```rust,no_run //! use std::{fs, path::Path, sync::Arc}; //! //! use parquet::{ //! file::{ //! properties::WriterProperties, //! writer::{FileWriter, SerializedFileWriter}, //! }, //! schema::parser::parse_message_type, //! }; //! //! let path = Path::new("/path/to/sample.parquet"); //! //! let message_type = " //! message schema { //! REQUIRED INT32 b; //! } //! "; //! let schema = Arc::new(parse_message_type(message_type).unwrap()); //! let props = Arc::new(WriterProperties::builder().build()); //! let file = fs::File::create(&path).unwrap(); //! let mut writer = SerializedFileWriter::new(file, schema, props).unwrap(); //! let mut row_group_writer = writer.next_row_group().unwrap(); //! while let Some(mut col_writer) = row_group_writer.next_column().unwrap() { //! // ... write values to a column writer //! row_group_writer.close_column(col_writer).unwrap(); //! } //! writer.close_row_group(row_group_writer).unwrap(); //! writer.close().unwrap(); //! //! let bytes = fs::read(&path).unwrap(); //! assert_eq!(&bytes[0..4], &[b'P', b'A', b'R', b'1']); //! ``` //! # Example of reading an existing file //! //! ```rust,no_run //! use parquet::file::reader::{FileReader, SerializedFileReader}; //! use std::{fs::File, path::Path}; //! //! let path = Path::new("/path/to/sample.parquet"); //! if let Ok(file) = File::open(&path) { //! let reader = SerializedFileReader::new(file).unwrap(); //! //! let parquet_metadata = reader.metadata(); //! assert_eq!(parquet_metadata.num_row_groups(), 1); //! //! let row_group_reader = reader.get_row_group(0).unwrap(); //! assert_eq!(row_group_reader.num_columns(), 1); //! } //! ``` //! # Example of reading multiple files //! //! ```rust,no_run //! use parquet::file::reader::SerializedFileReader; //! use std::convert::TryFrom; //! //! let paths = vec![ //! "/path/to/sample.parquet/part-1.snappy.parquet", //! "/path/to/sample.parquet/part-2.snappy.parquet" //! ]; //! // Create a reader for each file and flat map rows //! let rows = paths.iter() //! .map(|p| SerializedFileReader::try_from(*p).unwrap()) //! .flat_map(|r| r.into_iter()); //! //! for row in rows { //! println!("{}", row); //! } //! ``` pub mod footer; pub mod metadata; pub mod properties; pub mod reader; pub mod serialized_reader; pub mod statistics; pub mod writer; const FOOTER_SIZE: usize = 8; const PARQUET_MAGIC: [u8; 4] = [b'P', b'A', b'R', b'1']; /// The number of bytes read at the end of the parquet file on first read const DEFAULT_FOOTER_READ_SIZE: usize = 64 * 1024;