| // 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. |
| |
| //! Binary file to read data from a Parquet file. |
| //! |
| //! # Install |
| //! |
| //! `parquet-read` can be installed using `cargo`: |
| //! ``` |
| //! cargo install parquet |
| //! ``` |
| //! After this `parquet-read` should be globally available: |
| //! ``` |
| //! parquet-read XYZ.parquet |
| //! ``` |
| //! |
| //! The binary can also be built from the source code and run as follows: |
| //! ``` |
| //! cargo run --bin parquet-read XYZ.parquet |
| //! ``` |
| //! |
| //! # Usage |
| //! ``` |
| //! parquet-read <file-path> [num-records] |
| //! ``` |
| //! |
| //! ## Flags |
| //! -h, --help Prints help information |
| //! -j, --json Print Parquet file in JSON lines Format |
| //! -V, --version Prints version information |
| //! |
| //! ## Args |
| //! <file-path> Path to a Parquet file |
| //! <num-records> Number of records to read. When not provided, all records are read. |
| //! |
| //! Note that `parquet-read` reads full file schema, no projection or filtering is |
| //! applied. |
| |
| extern crate parquet; |
| |
| use std::{env, fs::File, path::Path}; |
| |
| use clap::{crate_authors, crate_version, App, Arg}; |
| |
| use parquet::file::reader::{FileReader, SerializedFileReader}; |
| use parquet::record::Row; |
| |
| fn main() { |
| let app = App::new("parquet-read") |
| .version(crate_version!()) |
| .author(crate_authors!()) |
| .about("Read data from a Parquet file and print output in console, in either built-in or JSON format") |
| .arg( |
| Arg::with_name("file_path") |
| .value_name("file-path") |
| .required(true) |
| .index(1) |
| .help("Path to a parquet file"), |
| ) |
| .arg( |
| Arg::with_name("num_records") |
| .value_name("num-records") |
| .index(2) |
| .help( |
| "Number of records to read. When not provided, all records are read.", |
| ), |
| ) |
| .arg( |
| Arg::with_name("json") |
| .short("j") |
| .long("json") |
| .takes_value(false) |
| .help("Print Parquet file in JSON lines format"), |
| ); |
| |
| let matches = app.get_matches(); |
| let filename = matches.value_of("file_path").unwrap(); |
| let num_records: Option<usize> = if matches.is_present("num_records") { |
| match matches.value_of("num_records").unwrap().parse() { |
| Ok(value) => Some(value), |
| Err(e) => panic!("Error when reading value for [num-records], {}", e), |
| } |
| } else { |
| None |
| }; |
| |
| let json = matches.is_present("json"); |
| let path = Path::new(&filename); |
| let file = File::open(&path).unwrap(); |
| let parquet_reader = SerializedFileReader::new(file).unwrap(); |
| |
| // Use full schema as projected schema |
| let mut iter = parquet_reader.get_row_iter(None).unwrap(); |
| |
| let mut start = 0; |
| let end = num_records.unwrap_or(0); |
| let all_records = num_records.is_none(); |
| |
| while all_records || start < end { |
| match iter.next() { |
| Some(row) => print_row(&row, json), |
| None => break, |
| } |
| start += 1; |
| } |
| } |
| |
| fn print_row(row: &Row, json: bool) { |
| if json { |
| println!("{}", row.to_json_value()) |
| } else { |
| println!("{}", row.to_string()); |
| } |
| } |