alamb commented on code in PR #7524:
URL: https://github.com/apache/arrow-rs/pull/7524#discussion_r2095501882
##########
parquet/src/arrow/arrow_reader/mod.rs:
##########
@@ -808,58 +841,92 @@ impl ParquetRecordBatchReader {
fn next_inner(&mut self) -> Result<Option<RecordBatch>> {
let mut read_records = 0;
let batch_size = self.batch_size();
+
+ let mut mask_builder = BooleanBufferBuilder::new(batch_size);
+
match self.read_plan.selection_mut() {
Some(selection) => {
- while read_records < batch_size && !selection.is_empty() {
- let front = selection.pop_front().unwrap();
- if front.skip {
- let skipped =
self.array_reader.skip_records(front.row_count)?;
+ while let Some(cur_selection) =
+ take_next_selection(selection, batch_size - read_records)
+ {
+ let mut total_read = 0;
+ let mut total_skip = 0;
+ for r in cur_selection.iter() {
+ if r.skip {
+ total_skip += r.row_count;
+ } else {
+ total_read += r.row_count;
+ }
+ }
+ let select_count = cur_selection.iter().count();
+ let total = total_skip + total_read;
- if skipped != front.row_count {
- return Err(general_err!(
+ if total < 10 * select_count {
+ let mut bitmap_builder =
BooleanBufferBuilder::new(total);
Review Comment:
Since many of these read selections come from a BooleanBuffer originally
(the result of evaluating a ArrowPredicate), I wonder what you think about
potentially avoiding creating `RowSelection`s in the ReadPlan
Something like
```rust
enum DecodeRows {
/// Decode exactly the rows accoding to the row selection
RowSelection(RowSelection),
/// Decode all rows, and then apply a filter to keep only the ones that
matter
Bitmask(BooleanBuffer)
}
impl ReadPlan {
// instead of Selection, have DecodeRows
decode_plan: VecDeque<DecodeRows>;
}
```
And then the trick would be some sort of heuristic / adaptive approach to
turn the result of the ArrowPredicate into a `DecodeRows` plan
https://github.com/apache/arrow-rs/blob/7bab215351876ffbef8e4e5898bdc1bf766557f5/parquet/src/arrow/arrow_reader/mod.rs#L1013-L1017
🤔
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