andygrove commented on code in PR #1181:
URL: https://github.com/apache/datafusion-comet/pull/1181#discussion_r1890829417
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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:
Yes, that is something I have been thinking about as well. We have the cost
of writing the schema for each batch currently, and the schema is guaranteed to
be the same for each batch.
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