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Use Row Format in SortExec #7053
Description
Activity
AFAIK this is implemented
Hm looking at the code, this doesn't seem to be the case
take
I probably need a efficient way to efficiently spill Rows to disk. Right now I am using a dumb way to spill Rows (len + row_data)
Current design is
- substitute
SendableRecordBatchStreambetweenSortPreservingMergeExecandSortExectoRowOrColumnStream
pub enum RowOrColumn { Row(Rows), Column(RecordBatch), } /// Contains a Rows or a Recordbatch pub type RowOrColumnStream = Pin<Box<dyn Stream<Item = Result<RowOrColumn>> + Send>>;
- In the begining of SortExec, we build the RowConverter, (if it is a single column sort, we don't build this and send a Recordbatch)
- for every recordbatch
SortExecrecieved, we convert it into Rows and do spill logic using Rows format(I implemented a rudimentary reader and writer for Rows) - in
SortPreservingMergeExecwe convert the rows to [[ArrayRef]] (We have to do this since I didn't find any arrow methods to directly build Recordbatch from Rows(probably we can implement one and don't need to store extra columns?)) and didn't break any loser_tree logics.
- substitute
Is your feature request related to a problem or challenge?
Currently
SortExec::sort_batch_streamuseslexsort_to_indicesto sort the producedRecordBatch. For multi-column sorts this makes use ofLexicographicalComparator. The branching and dynamic dispatch involved in this comparator is relatively expensive. Converting to the row format first, and comparing these rows has been found to offer significant performance advantages in similar applications - #3386.Describe the solution you'd like
SortExec should:
sort_to_indicesto sort the input batchesDescribe alternatives you've considered
No response
Additional context
This is likely not a good first issue, and I do not recommend people pick it up, creating primarily for tracking purposes. I will likely pick it up at some point in the near-ish future.