andygrove commented on code in PR #1181:
URL: https://github.com/apache/datafusion-comet/pull/1181#discussion_r1890865548
##########
native/core/src/execution/shuffle/shuffle_writer.rs:
##########
@@ -1543,14 +1569,38 @@ pub(crate) fn write_ipc_compressed<W: Write + Seek>(
// write ipc_length placeholder
output.write_all(&[0u8; 8])?;
- // write ipc data
- // TODO: make compression level configurable
- let mut arrow_writer = StreamWriter::try_new(zstd::Encoder::new(output,
1)?, &batch.schema())?;
- arrow_writer.write(batch)?;
- arrow_writer.finish()?;
+ let output = match codec {
+ CompressionCodec::Lz4 => {
+ // write IPC first without compression
+ let mut buffer = vec![];
+ let mut arrow_writer = StreamWriter::try_new(&mut buffer,
&batch.schema())?;
+ arrow_writer.write(batch)?;
+ arrow_writer.finish()?;
+ let ipc_encoded = arrow_writer.into_inner()?;
+
+ let mut encoder = lz4::EncoderBuilder::new()
+ .content_size(ipc_encoded.len() as u64)
+ .checksum(ContentChecksum::ChecksumEnabled)
+ .block_checksum(BlockChecksum::BlockChecksumEnabled)
+ .level(4)
+ .block_size(BlockSize::Default)
+ .auto_flush(true)
+ .build(&mut *output)?;
+ encoder.write_all(ipc_encoded.as_slice())?;
+ let (output, result) = encoder.finish();
+ result?;
+ output
+ }
+ CompressionCodec::Zstd(level) => {
+ let encoder = zstd::Encoder::new(output, *level)?;
+ let mut arrow_writer = StreamWriter::try_new(encoder,
&batch.schema())?;
Review Comment:
To add some more context here, we buffer rows per partition until we reach
the desired batch size and then need to serialize that batch to bytes that can
be read as one block by `CometBlockStoreShuffleReader`.
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