Ted-Jiang commented on code in PR #1998:
URL: https://github.com/apache/arrow-rs/pull/1998#discussion_r913362921
##########
parquet/src/arrow/record_reader/mod.rs:
##########
@@ -202,6 +203,37 @@ where
Ok(records_read)
}
+ /// Try to skip the next `num_records` rows
+ ///
+ /// # Returns
+ ///
+ /// Number of records skipped
+ pub fn skip_records(&mut self, num_records: usize) -> Result<usize> {
+ // First need to clear the buffer
+ let (buffered_records, buffered_values) =
self.count_records(num_records);
+ self.num_records += buffered_records;
+ self.num_values += buffered_values;
+
+ self.consume_def_levels();
+ self.consume_rep_levels();
+ self.consume_record_data();
Review Comment:
👍 nice write up ! Save me some time 😄!
So, i got it. More specific details to ask:
This is a part of skip, we need to read the `rp` ,`dp` to skip some records
in the page(maybe have been readed or never readed ).
```
let (buffered_records, buffered_values) = self.count_records(num_records);
self.num_records += buffered_records;
self.num_values += buffered_values;
self.consume_def_levels();
self.consume_rep_levels();
self.consume_record_data();
self.consume_bitmap();
self.reset();
let remaining = buffered_records - num_records;
```
This also part of skip, `remaining > 0`, I think this we skip start at a new
page
```
if remaining == 0 {
return Ok(buffered_records);
}
let skipped = match self.column_reader.as_mut() {
Some(column_reader) => column_reader.skip_records(remaining)?,
None => 0,
};
```
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