<!---
  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.
-->

# An Apache Parquet implementation in Rust

## Usage
Add this to your Cargo.toml:
```toml
[dependencies]
parquet = "4.0.1"
```

and this to your crate root:
```rust
extern crate parquet;
```

Example usage of reading data:
```rust
use std::fs::File;
use std::path::Path;
use parquet::file::reader::{FileReader, SerializedFileReader};

let file = File::open(&Path::new("/path/to/file")).unwrap();
let reader = SerializedFileReader::new(file).unwrap();
let mut iter = reader.get_row_iter(None).unwrap();
while let Some(record) = iter.next() {
    println!("{}", record);
}
```
See [crate documentation](https://docs.rs/crate/parquet/4.0.1) on available API.

## Upgrading from versions prior to 4.0

If you are upgrading from version 3.0 or previous of this crate, you
likely need to change your code to use [`ConvertedType`] rather than
[`LogicalType`] to preserve existing behaviour in your code.

Version 2.4.0 of the Parquet format introduced a `LogicalType` to replace the existing `ConvertedType`.
This crate used `parquet::basic::LogicalType` to map to the `ConvertedType`, but this has been renamed to `parquet::basic::ConvertedType` from version 4.0 of this crate.

The `ConvertedType` is deprecated in the format, but is still written
to preserve backward compatibility.
It is preferred that `LogicalType` is used, as it supports nanosecond
precision timestamps without using the deprecated `Int96` Parquet type.

## Supported Parquet Version
- Parquet-format 2.6.0

To update Parquet format to a newer version, check if [parquet-format](https://github.com/sunchao/parquet-format-rs)
version is available. Then simply update version of `parquet-format` crate in Cargo.toml.

## Features
- [X] All encodings supported
- [X] All compression codecs supported
- [X] Read support
  - [X] Primitive column value readers
  - [X] Row record reader
  - [X] Arrow record reader
- [ ] Statistics support
- [X] Write support
  - [X] Primitive column value writers
  - [ ] Row record writer
  - [X] Arrow record writer
- [ ] Predicate pushdown
- [X] Parquet format 2.6.0 support

## Requirements

Parquet requires LLVM.  Our windows CI image includes LLVM but to build the libraries locally windows
users will have to install LLVM. Follow [this](https://github.com/appveyor/ci/issues/2651) link for info.

## Build
Run `cargo build` or `cargo build --release` to build in release mode.
Some features take advantage of SSE4.2 instructions, which can be
enabled by adding `RUSTFLAGS="-C target-feature=+sse4.2"` before the
`cargo build` command.

## Test
Run `cargo test` for unit tests. To also run tests related to the binaries, use `cargo test --features cli`.

## Binaries
The following binaries are provided (use `cargo install --features cli` to install them):
- **parquet-schema** for printing Parquet file schema and metadata.
`Usage: parquet-schema <file-path>`, where `file-path` is the path to a Parquet file. Use `-v/--verbose` flag
to print full metadata or schema only (when not specified only schema will be printed).

- **parquet-read** for reading records from a Parquet file.
`Usage: parquet-read <file-path> [num-records]`, where `file-path` is the path to a Parquet file,
and `num-records` is the number of records to read from a file (when not specified all records will
be printed). Use `-j/--json` to print records in JSON lines format.

- **parquet-rowcount** for reporting the number of records in one or more Parquet files.
`Usage: parquet-rowcount <file-paths>...`, where `<file-paths>...` is a space separated list of one or more
files to read.

If you see `Library not loaded` error, please make sure `LD_LIBRARY_PATH` is set properly:
```
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$(rustc --print sysroot)/lib
```

## Benchmarks
Run `cargo bench` for benchmarks.

## Docs
To build documentation, run `cargo doc --no-deps`.
To compile and view in the browser, run `cargo doc --no-deps --open`.

## License
Licensed under the Apache License, Version 2.0: http://www.apache.org/licenses/LICENSE-2.0.
