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Preserve dictionary encoding when decoding parquet into Arrow arrays, 60x perf improvement (#171) #1180

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Jan 24, 2022
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Preserve dictionary encoding when decoding parquet into Arrow arrays, 60x perf improvement (#171) #1180

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3142ec0
Preserve dictionary encoding from parquet (#171)
tustvold Jan 12, 2022
f6b68c3
Use OffsetBuffer::into_array for dictionary
tustvold Jan 18, 2022
4b183bd
Fix and test handling of empty dictionaries
tustvold Jan 20, 2022
f8b5cd8
Use ArrayRef instead of Arc<ArrayData>
tustvold Jan 20, 2022
93c8dd3
Update doc comments
tustvold Jan 20, 2022
de33346
Add integration test
tustvold Jan 20, 2022
761bd90
Add benchmark
tustvold Jan 21, 2022
bf28e16
Set write batch size in parquet fuzz tests
tustvold Jan 21, 2022
c07b1b5
Fix test_dictionary_preservation
tustvold Jan 21, 2022
8985aee
Add batch_size comment
tustvold Jan 21, 2022
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68 changes: 26 additions & 42 deletions parquet/src/arrow/array_reader.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -56,11 +56,10 @@ use arrow::datatypes::{
use arrow::util::bit_util;

use crate::arrow::converter::{
BinaryArrayConverter, BinaryConverter, Converter, DecimalArrayConverter,
DecimalConverter, FixedLenBinaryConverter, FixedSizeArrayConverter,
Int96ArrayConverter, Int96Converter, IntervalDayTimeArrayConverter,
IntervalDayTimeConverter, IntervalYearMonthArrayConverter,
IntervalYearMonthConverter, Utf8ArrayConverter, Utf8Converter,
Converter, DecimalArrayConverter, DecimalConverter, FixedLenBinaryConverter,
FixedSizeArrayConverter, Int96ArrayConverter, Int96Converter,
IntervalDayTimeArrayConverter, IntervalDayTimeConverter,
IntervalYearMonthArrayConverter, IntervalYearMonthConverter,
};
use crate::arrow::record_reader::buffer::{ScalarValue, ValuesBuffer};
use crate::arrow::record_reader::{GenericRecordReader, RecordReader};
Expand All @@ -70,8 +69,8 @@ use crate::column::page::PageIterator;
use crate::column::reader::decoder::ColumnValueDecoder;
use crate::column::reader::ColumnReaderImpl;
use crate::data_type::{
BoolType, ByteArrayType, DataType, DoubleType, FixedLenByteArrayType, FloatType,
Int32Type, Int64Type, Int96Type,
BoolType, DataType, DoubleType, FixedLenByteArrayType, FloatType, Int32Type,
Int64Type, Int96Type,
};
use crate::errors::{ParquetError, ParquetError::ArrowError, Result};
use crate::file::reader::{FilePageIterator, FileReader};
Expand All @@ -81,9 +80,15 @@ use crate::schema::types::{
use crate::schema::visitor::TypeVisitor;

mod byte_array;
mod byte_array_dictionary;
mod dictionary_buffer;
mod offset_buffer;

#[cfg(test)]
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mod test_util;

pub use byte_array::make_byte_array_reader;
pub use byte_array_dictionary::make_byte_array_dictionary_reader;

/// Array reader reads parquet data into arrow array.
pub trait ArrayReader {
Expand Down Expand Up @@ -271,7 +276,8 @@ where
.clone(),
};

let record_reader = RecordReader::<T>::new_with_options(column_desc.clone(), null_mask_only);
let record_reader =
RecordReader::<T>::new_with_options(column_desc.clone(), null_mask_only);

Ok(Self {
data_type,
Expand Down Expand Up @@ -829,17 +835,18 @@ fn remove_indices(
size
),
ArrowType::Struct(fields) => {
let struct_array = arr.as_any()
let struct_array = arr
.as_any()
.downcast_ref::<StructArray>()
.expect("Array should be a struct");

// Recursively call remove indices on each of the structs fields
let new_columns = fields.into_iter()
let new_columns = fields
.into_iter()
.zip(struct_array.columns())
.map(|(field, column)| {
let dt = field.data_type().clone();
Ok((field,
remove_indices(column.clone(), dt, indices.clone())?))
Ok((field, remove_indices(column.clone(), dt, indices.clone())?))
})
.collect::<Result<Vec<_>>>()?;

Expand Down Expand Up @@ -1783,35 +1790,12 @@ impl<'a> ArrayReaderBuilder {
)?,
)),
PhysicalType::BYTE_ARRAY => match arrow_type {
// TODO: Replace with optimised dictionary reader (#171)
Some(ArrowType::Dictionary(_, _)) => {
match cur_type.get_basic_info().converted_type() {
ConvertedType::UTF8 => {
let converter = Utf8Converter::new(Utf8ArrayConverter {});
Ok(Box::new(ComplexObjectArrayReader::<
ByteArrayType,
Utf8Converter,
>::new(
page_iterator,
column_desc,
converter,
arrow_type,
)?))
}
_ => {
let converter = BinaryConverter::new(BinaryArrayConverter {});
Ok(Box::new(ComplexObjectArrayReader::<
ByteArrayType,
BinaryConverter,
>::new(
page_iterator,
column_desc,
converter,
arrow_type,
)?))
}
}
}
Some(ArrowType::Dictionary(_, _)) => make_byte_array_dictionary_reader(
page_iterator,
column_desc,
arrow_type,
null_mask_only,
),
_ => make_byte_array_reader(
page_iterator,
column_desc,
Expand Down Expand Up @@ -2025,7 +2009,7 @@ mod tests {
use crate::arrow::schema::parquet_to_arrow_schema;
use crate::basic::{Encoding, Type as PhysicalType};
use crate::column::page::{Page, PageReader};
use crate::data_type::{ByteArray, DataType, Int32Type, Int64Type};
use crate::data_type::{ByteArray, ByteArrayType, DataType, Int32Type, Int64Type};
use crate::errors::Result;
use crate::file::reader::{FileReader, SerializedFileReader};
use crate::schema::parser::parse_message_type;
Expand Down
71 changes: 7 additions & 64 deletions parquet/src/arrow/array_reader/byte_array.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -579,69 +579,18 @@ impl ByteArrayDecoderDictionary {
#[cfg(test)]
mod tests {
use super::*;
use crate::arrow::array_reader::test_util::{
byte_array_all_encodings, utf8_column,
};
use crate::arrow::record_reader::buffer::ValuesBuffer;
use crate::basic::Type as PhysicalType;
use crate::data_type::{ByteArray, ByteArrayType};
use crate::encodings::encoding::{get_encoder, DictEncoder, Encoder};
use crate::schema::types::{ColumnDescriptor, ColumnPath, Type};
use crate::util::memory::MemTracker;
use arrow::array::{Array, StringArray};
use std::sync::Arc;

fn column() -> ColumnDescPtr {
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This code is extracted out into test_utils

let t = Type::primitive_type_builder("col", PhysicalType::BYTE_ARRAY)
.with_converted_type(ConvertedType::UTF8)
.build()
.unwrap();

Arc::new(ColumnDescriptor::new(
Arc::new(t),
1,
0,
ColumnPath::new(vec![]),
))
}

fn get_encoded(encoding: Encoding, data: &[ByteArray]) -> ByteBufferPtr {
let descriptor = column();
let mem_tracker = Arc::new(MemTracker::new());
let mut encoder =
get_encoder::<ByteArrayType>(descriptor, encoding, mem_tracker).unwrap();

encoder.put(data).unwrap();
encoder.flush_buffer().unwrap()
}

#[test]
fn test_byte_array_decoder() {
let data: Vec<_> = vec!["hello", "world", "a", "b"]
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This code is extracted out into test_utils so that it can be reused

.into_iter()
.map(ByteArray::from)
.collect();

let mut dict_encoder =
DictEncoder::<ByteArrayType>::new(column(), Arc::new(MemTracker::new()));

dict_encoder.put(&data).unwrap();
let encoded_rle = dict_encoder.flush_buffer().unwrap();
let encoded_dictionary = dict_encoder.write_dict().unwrap();

// A column chunk with all the encodings!
let pages = vec![
(Encoding::PLAIN, get_encoded(Encoding::PLAIN, &data)),
(
Encoding::DELTA_BYTE_ARRAY,
get_encoded(Encoding::DELTA_BYTE_ARRAY, &data),
),
(
Encoding::DELTA_LENGTH_BYTE_ARRAY,
get_encoded(Encoding::DELTA_LENGTH_BYTE_ARRAY, &data),
),
(Encoding::PLAIN_DICTIONARY, encoded_rle.clone()),
(Encoding::RLE_DICTIONARY, encoded_rle),
];
let (pages, encoded_dictionary) =
byte_array_all_encodings(vec!["hello", "world", "a", "b"]);

let column_desc = column();
let column_desc = utf8_column();
let mut decoder = ByteArrayColumnValueDecoder::new(&column_desc);

decoder
Expand All @@ -668,15 +617,9 @@ mod tests {
assert_eq!(decoder.read(&mut output, 4..8).unwrap(), 0);

let valid = vec![false, false, true, true, false, true, true, false, false];
let rev_position_iter = valid
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This is an example of how changing pad_nulls to take a packed bitmask makes the tests less verbose

.iter()
.enumerate()
.rev()
.filter_map(|(i, valid)| valid.then(|| i));

let valid_buffer = Buffer::from_iter(valid.iter().cloned());

output.pad_nulls(0, 4, valid.len(), rev_position_iter);
output.pad_nulls(0, 4, valid.len(), valid_buffer.as_slice());
let array = output.into_array(Some(valid_buffer), ArrowType::Utf8);
let strings = array.as_any().downcast_ref::<StringArray>().unwrap();

Expand Down
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