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Combine multiple selections into the same batch size in skip_records #2358

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Ted-Jiang opened this issue Aug 8, 2022 · 0 comments · Fixed by #2359
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Combine multiple selections into the same batch size in skip_records #2358

Ted-Jiang opened this issue Aug 8, 2022 · 0 comments · Fixed by #2359
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enhancement Any new improvement worthy of a entry in the changelog parquet Changes to the parquet crate

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@Ted-Jiang
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The skip records API added to the ArrayReader trait as part of #1998 does not provide a way to combine multiple selections into the same batch. This is unfortunate as columnar query engines will often want consistently large RecordBatch so that any dispatch overheads can be amortised over many rows. Whilst it could concatenate batches together, e.g. DataFusion's CoalesceBatchesExec, it would be more efficient to do this directly on read and eliminate an additional copy.

Originally posted by @tustvold in #2197 (comment)

@alamb alamb added parquet Changes to the parquet crate enhancement Any new improvement worthy of a entry in the changelog labels Aug 10, 2022
@alamb alamb changed the title Combine multiple selections into the same batch size in skip_records Combine multiple selections into the same batch size in skip_records Aug 17, 2022
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Labels
enhancement Any new improvement worthy of a entry in the changelog parquet Changes to the parquet crate
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