tustvold commented on issue #4365:
URL: https://github.com/apache/arrow-rs/issues/4365#issuecomment-1576812180
Thank you for the report, yes I would expect this to work correctly
A reduced example:
```
use arrow::array::{ListBuilder, StringBuilder};
use arrow::datatypes::{DataType, Field, Schema};
use arrow::record_batch::RecordBatch;
use std::sync::Arc;
use bytes::Bytes;
use parquet::arrow::arrow_reader::{
ParquetRecordBatchReaderBuilder, RowSelection, RowSelector,
};
use parquet::arrow::ArrowWriter;
use parquet::file::properties::WriterProperties;
use std::error::Error;
fn main() -> Result<(), Box<dyn Error>> {
let schema = Arc::new(Schema::new(vec![Field::new_list(
"list",
Field::new("item", DataType::Utf8, true),
false,
)]));
let mut buf = Vec::with_capacity(1024);
let mut writer = ArrowWriter::try_new(
&mut buf,
schema.clone(),
Some(WriterProperties::builder().build()),
)?;
for _ in 0..2 {
let mut list_a_builder = ListBuilder::new(StringBuilder::new());
for i in 0..1024 {
list_a_builder.values().append_value(format!("{i}"));
list_a_builder.append(true);
}
let batch = RecordBatch::try_new(
schema.clone(),
vec![Arc::new(list_a_builder.finish())],
)?;
writer.write(&batch)?;
}
let _metadata = writer.close()?;
let buf = Bytes::from(buf);
let reader = ParquetRecordBatchReaderBuilder::try_new(buf)
.unwrap()
.with_row_selection(RowSelection::from(vec![
RowSelector::skip(100),
RowSelector::select(924),
RowSelector::skip(100),
RowSelector::select(924),
]))
.build()
.unwrap();
let total_rows: usize = reader.map(|r| r.unwrap().num_rows()).sum();
assert_eq!(total_rows, 924 * 2);
Ok(())
}
```
It also does not seem to be specific to lists of strings.
I will continue digging
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