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* Generify parquet write path (#1764) * More docs * Lint * Fix doc * Review feedback * Fix doc
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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. | ||
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use crate::basic::Encoding; | ||
use crate::column::writer::{ | ||
compare_greater, fallback_encoding, has_dictionary_support, is_nan, update_max, | ||
update_min, | ||
}; | ||
use crate::data_type::private::ParquetValueType; | ||
use crate::data_type::DataType; | ||
use crate::encodings::encoding::{get_encoder, DictEncoder, Encoder}; | ||
use crate::errors::{ParquetError, Result}; | ||
use crate::file::properties::WriterProperties; | ||
use crate::schema::types::{ColumnDescPtr, ColumnDescriptor}; | ||
use crate::util::memory::ByteBufferPtr; | ||
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/// A collection of [`ParquetValueType`] encoded by a [`ColumnValueEncoder`] | ||
pub trait ColumnValues { | ||
/// The underlying value type | ||
type T: ParquetValueType; | ||
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/// The number of values in this collection | ||
fn len(&self) -> usize; | ||
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/// Returns the min and max values in this collection, skipping any NaN values | ||
/// | ||
/// Returns `None` if no values found | ||
fn min_max(&self, descr: &ColumnDescriptor) -> Option<(&Self::T, &Self::T)>; | ||
} | ||
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/// The encoded data for a dictionary page | ||
pub struct DictionaryPage { | ||
pub buf: ByteBufferPtr, | ||
pub num_values: usize, | ||
pub is_sorted: bool, | ||
} | ||
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/// The encoded values for a data page, with optional statistics | ||
pub struct DataPageValues<T> { | ||
pub buf: ByteBufferPtr, | ||
pub num_values: usize, | ||
pub encoding: Encoding, | ||
pub min_value: Option<T>, | ||
pub max_value: Option<T>, | ||
} | ||
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/// A generic encoder of [`ColumnValues`] to data and dictionary pages used by | ||
/// [super::GenericColumnWriter`] | ||
pub trait ColumnValueEncoder { | ||
/// The underlying value type of [`Self::Values`] | ||
/// | ||
/// Note: this avoids needing to fully qualify `<Self::Values as ColumnValues>::T` | ||
type T: ParquetValueType; | ||
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/// The values encoded by this encoder | ||
type Values: ColumnValues<T = Self::T> + ?Sized; | ||
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/// Create a new [`ColumnValueEncoder`] | ||
fn try_new(descr: &ColumnDescPtr, props: &WriterProperties) -> Result<Self> | ||
where | ||
Self: Sized; | ||
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/// Write the corresponding values to this [`ColumnValueEncoder`] | ||
fn write(&mut self, values: &Self::Values, offset: usize, len: usize) -> Result<()>; | ||
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/// Returns the number of buffered values | ||
fn num_values(&self) -> usize; | ||
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/// Returns true if this encoder has a dictionary page | ||
fn has_dictionary(&self) -> bool; | ||
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/// Returns an estimate of the dictionary page size in bytes, or `None` if no dictionary | ||
fn estimated_dict_page_size(&self) -> Option<usize>; | ||
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/// Returns an estimate of the data page size in bytes | ||
fn estimated_data_page_size(&self) -> usize; | ||
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/// Flush the dictionary page for this column chunk if any. Any subsequent calls to | ||
/// [`Self::write`] will not be dictionary encoded | ||
/// | ||
/// Note: [`Self::flush_data_page`] must be called first, as this will error if there | ||
/// are any pending page values | ||
fn flush_dict_page(&mut self) -> Result<Option<DictionaryPage>>; | ||
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/// Flush the next data page for this column chunk | ||
fn flush_data_page(&mut self) -> Result<DataPageValues<Self::T>>; | ||
} | ||
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pub struct ColumnValueEncoderImpl<T: DataType> { | ||
encoder: Box<dyn Encoder<T>>, | ||
dict_encoder: Option<DictEncoder<T>>, | ||
descr: ColumnDescPtr, | ||
num_values: usize, | ||
min_value: Option<T::T>, | ||
max_value: Option<T::T>, | ||
} | ||
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impl<T: DataType> ColumnValueEncoder for ColumnValueEncoderImpl<T> { | ||
type T = T::T; | ||
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type Values = [T::T]; | ||
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fn try_new(descr: &ColumnDescPtr, props: &WriterProperties) -> Result<Self> { | ||
let dict_supported = props.dictionary_enabled(descr.path()) | ||
&& has_dictionary_support(T::get_physical_type(), props); | ||
let dict_encoder = dict_supported.then(|| DictEncoder::new(descr.clone())); | ||
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// Set either main encoder or fallback encoder. | ||
let encoder = get_encoder( | ||
descr.clone(), | ||
props | ||
.encoding(descr.path()) | ||
.unwrap_or_else(|| fallback_encoding(T::get_physical_type(), props)), | ||
)?; | ||
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Ok(Self { | ||
encoder, | ||
dict_encoder, | ||
descr: descr.clone(), | ||
num_values: 0, | ||
min_value: None, | ||
max_value: None, | ||
}) | ||
} | ||
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fn write(&mut self, values: &[T::T], offset: usize, len: usize) -> Result<()> { | ||
self.num_values += len; | ||
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let slice = values.get(offset..offset + len).ok_or_else(|| { | ||
general_err!( | ||
"Expected to write {} values, but have only {}", | ||
len, | ||
values.len() - offset | ||
) | ||
})?; | ||
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if let Some((min, max)) = slice.min_max(&self.descr) { | ||
update_min(&self.descr, min, &mut self.min_value); | ||
update_max(&self.descr, max, &mut self.max_value); | ||
} | ||
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match &mut self.dict_encoder { | ||
Some(encoder) => encoder.put(slice), | ||
_ => self.encoder.put(slice), | ||
} | ||
} | ||
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fn num_values(&self) -> usize { | ||
self.num_values | ||
} | ||
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fn has_dictionary(&self) -> bool { | ||
self.dict_encoder.is_some() | ||
} | ||
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fn estimated_dict_page_size(&self) -> Option<usize> { | ||
Some(self.dict_encoder.as_ref()?.dict_encoded_size()) | ||
} | ||
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fn estimated_data_page_size(&self) -> usize { | ||
match &self.dict_encoder { | ||
Some(encoder) => encoder.estimated_data_encoded_size(), | ||
_ => self.encoder.estimated_data_encoded_size(), | ||
} | ||
} | ||
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fn flush_dict_page(&mut self) -> Result<Option<DictionaryPage>> { | ||
match self.dict_encoder.take() { | ||
Some(encoder) => { | ||
if self.num_values != 0 { | ||
return Err(general_err!( | ||
"Must flush data pages before flushing dictionary" | ||
)); | ||
} | ||
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let buf = encoder.write_dict()?; | ||
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Ok(Some(DictionaryPage { | ||
buf, | ||
num_values: encoder.num_entries(), | ||
is_sorted: encoder.is_sorted(), | ||
})) | ||
} | ||
_ => Ok(None), | ||
} | ||
} | ||
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fn flush_data_page(&mut self) -> Result<DataPageValues<T::T>> { | ||
let (buf, encoding) = match &mut self.dict_encoder { | ||
Some(encoder) => (encoder.write_indices()?, Encoding::RLE_DICTIONARY), | ||
_ => (self.encoder.flush_buffer()?, self.encoder.encoding()), | ||
}; | ||
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Ok(DataPageValues { | ||
buf, | ||
encoding, | ||
num_values: std::mem::take(&mut self.num_values), | ||
min_value: self.min_value.take(), | ||
max_value: self.max_value.take(), | ||
}) | ||
} | ||
} | ||
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impl<T: ParquetValueType> ColumnValues for [T] { | ||
type T = T; | ||
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fn len(&self) -> usize { | ||
self.len() | ||
} | ||
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fn min_max(&self, descr: &ColumnDescriptor) -> Option<(&T, &T)> { | ||
let mut iter = self.iter(); | ||
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let first = loop { | ||
let next = iter.next()?; | ||
if !is_nan(next) { | ||
break next; | ||
} | ||
}; | ||
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let mut min = first; | ||
let mut max = first; | ||
for val in iter { | ||
if is_nan(val) { | ||
continue; | ||
} | ||
if compare_greater(descr, min, val) { | ||
min = val; | ||
} | ||
if compare_greater(descr, val, max) { | ||
max = val; | ||
} | ||
} | ||
Some((min, max)) | ||
} | ||
} |
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